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2013-07-30freezer: set PF_SUSPEND_TASK flag on tasks that call freeze_processesColin Cross2-1/+12
Calling freeze_processes sets a global flag that will cause any process that calls try_to_freeze to enter the refrigerator. It skips sending a signal to the current task, but if the current task ever hits try_to_freeze, all threads will be frozen and the system will deadlock. Set a new flag, PF_SUSPEND_TASK, on the task that calls freeze_processes. The flag notifies the freezer that the thread is involved in suspend and should not be frozen. Also add a WARN_ON in thaw_processes if the caller does not have the PF_SUSPEND_TASK flag set to catch if a different task calls thaw_processes than the one that called freeze_processes, leaving a task with PF_SUSPEND_TASK permanently set on it. Threads that spawn off a task with PF_SUSPEND_TASK set (which swsusp does) will also have PF_SUSPEND_TASK set, preventing them from freezing while they are helping with suspend, but they need to be dead by the time suspend is triggered, otherwise they may run when userspace is expected to be frozen. Add a WARN_ON in thaw_processes if more than one thread has the PF_SUSPEND_TASK flag set. Reported-and-tested-by: Michael Leun <lkml20130126@newton.leun.net> Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-07-29Revert "cpuidle: Quickly notice prediction failure for repeat mode"Rafael J. Wysocki1-7/+2
Revert commit 69a37bea (cpuidle: Quickly notice prediction failure for repeat mode), because it has been identified as the source of a significant performance regression in v3.8 and later as explained by Jeremy Eder: We believe we've identified a particular commit to the cpuidle code that seems to be impacting performance of variety of workloads. The simplest way to reproduce is using netperf TCP_RR test, so we're using that, on a pair of Sandy Bridge based servers. We also have data from a large database setup where performance is also measurably/positively impacted, though that test data isn't easily share-able. Included below are test results from 3 test kernels: kernel reverts ----------------------------------------------------------- 1) vanilla upstream (no reverts) 2) perfteam2 reverts e11538d1f03914eb92af5a1a378375c05ae8520c 3) test reverts 69a37beabf1f0a6705c08e879bdd5d82ff6486c4 e11538d1f03914eb92af5a1a378375c05ae8520c In summary, netperf TCP_RR numbers improve by approximately 4% after reverting 69a37beabf1f0a6705c08e879bdd5d82ff6486c4. When 69a37beabf1f0a6705c08e879bdd5d82ff6486c4 is included, C0 residency never seems to get above 40%. Taking that patch out gets C0 near 100% quite often, and performance increases. The below data are histograms representing the %c0 residency @ 1-second sample rates (using turbostat), while under netperf test. - If you look at the first 4 histograms, you can see %c0 residency almost entirely in the 30,40% bin. - The last pair, which reverts 69a37beabf1f0a6705c08e879bdd5d82ff6486c4, shows %c0 in the 80,90,100% bins. Below each kernel name are netperf TCP_RR trans/s numbers for the particular kernel that can be disclosed publicly, comparing the 3 test kernels. We ran a 4th test with the vanilla kernel where we've also set /dev/cpu_dma_latency=0 to show overall impact boosting single-threaded TCP_RR performance over 11% above baseline. 3.10-rc2 vanilla RX + c0 lock (/dev/cpu_dma_latency=0): TCP_RR trans/s 54323.78 ----------------------------------------------------------- 3.10-rc2 vanilla RX (no reverts) TCP_RR trans/s 48192.47 Receiver %c0 0.0000 - 10.0000 [ 1]: * 10.0000 - 20.0000 [ 0]: 20.0000 - 30.0000 [ 0]: 30.0000 - 40.0000 [ 59]: *********************************************************** 40.0000 - 50.0000 [ 1]: * 50.0000 - 60.0000 [ 0]: 60.0000 - 70.0000 [ 0]: 70.0000 - 80.0000 [ 0]: 80.0000 - 90.0000 [ 0]: 90.0000 - 100.0000 [ 0]: Sender %c0 0.0000 - 10.0000 [ 1]: * 10.0000 - 20.0000 [ 0]: 20.0000 - 30.0000 [ 0]: 30.0000 - 40.0000 [ 11]: *********** 40.0000 - 50.0000 [ 49]: ************************************************* 50.0000 - 60.0000 [ 0]: 60.0000 - 70.0000 [ 0]: 70.0000 - 80.0000 [ 0]: 80.0000 - 90.0000 [ 0]: 90.0000 - 100.0000 [ 0]: ----------------------------------------------------------- 3.10-rc2 perfteam2 RX (reverts commit e11538d1f03914eb92af5a1a378375c05ae8520c) TCP_RR trans/s 49698.69 Receiver %c0 0.0000 - 10.0000 [ 1]: * 10.0000 - 20.0000 [ 1]: * 20.0000 - 30.0000 [ 0]: 30.0000 - 40.0000 [ 59]: *********************************************************** 40.0000 - 50.0000 [ 0]: 50.0000 - 60.0000 [ 0]: 60.0000 - 70.0000 [ 0]: 70.0000 - 80.0000 [ 0]: 80.0000 - 90.0000 [ 0]: 90.0000 - 100.0000 [ 0]: Sender %c0 0.0000 - 10.0000 [ 1]: * 10.0000 - 20.0000 [ 0]: 20.0000 - 30.0000 [ 0]: 30.0000 - 40.0000 [ 2]: ** 40.0000 - 50.0000 [ 58]: ********************************************************** 50.0000 - 60.0000 [ 0]: 60.0000 - 70.0000 [ 0]: 70.0000 - 80.0000 [ 0]: 80.0000 - 90.0000 [ 0]: 90.0000 - 100.0000 [ 0]: ----------------------------------------------------------- 3.10-rc2 test RX (reverts 69a37beabf1f0a6705c08e879bdd5d82ff6486c4 and e11538d1f03914eb92af5a1a378375c05ae8520c) TCP_RR trans/s 47766.95 Receiver %c0 0.0000 - 10.0000 [ 1]: * 10.0000 - 20.0000 [ 1]: * 20.0000 - 30.0000 [ 0]: 30.0000 - 40.0000 [ 27]: *************************** 40.0000 - 50.0000 [ 2]: ** 50.0000 - 60.0000 [ 0]: 60.0000 - 70.0000 [ 2]: ** 70.0000 - 80.0000 [ 0]: 80.0000 - 90.0000 [ 0]: 90.0000 - 100.0000 [ 28]: **************************** Sender: 0.0000 - 10.0000 [ 1]: * 10.0000 - 20.0000 [ 0]: 20.0000 - 30.0000 [ 0]: 30.0000 - 40.0000 [ 11]: *********** 40.0000 - 50.0000 [ 0]: 50.0000 - 60.0000 [ 1]: * 60.0000 - 70.0000 [ 0]: 70.0000 - 80.0000 [ 3]: *** 80.0000 - 90.0000 [ 7]: ******* 90.0000 - 100.0000 [ 38]: ************************************** These results demonstrate gaining back the tendency of the CPU to stay in more responsive, performant C-states (and thus yield measurably better performance), by reverting commit 69a37beabf1f0a6705c08e879bdd5d82ff6486c4. Requested-by: Jeremy Eder <jeder@redhat.com> Tested-by: Len Brown <len.brown@intel.com> Cc: 3.8+ <stable@vger.kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-07-29Merge tag 'trace-fixes-3.11-rc2' of ↵Linus Torvalds3-128/+95
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes from Steven Rostedt: "Oleg is working on fixing a very tight race between opening a event file and deleting that event at the same time (both must be done as root). I also found a bug while testing Oleg's patches which has to do with a race with kprobes using the function tracer. There's also a deadlock fix that was introduced with the previous fixes" * tag 'trace-fixes-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Remove locking trace_types_lock from tracing_reset_all_online_cpus() ftrace: Add check for NULL regs if ops has SAVE_REGS set tracing: Kill trace_cpu struct/members tracing: Change tracing_fops/snapshot_fops to rely on tracing_get_cpu() tracing: Change tracing_entries_fops to rely on tracing_get_cpu() tracing: Change tracing_stats_fops to rely on tracing_get_cpu() tracing: Change tracing_buffers_fops to rely on tracing_get_cpu() tracing: Change tracing_pipe_fops() to rely on tracing_get_cpu() tracing: Introduce trace_create_cpu_file() and tracing_get_cpu()
2013-07-26tracing: Remove locking trace_types_lock from tracing_reset_all_online_cpus()Steven Rostedt (Red Hat)1-2/+1
Commit a82274151af "tracing: Protect ftrace_trace_arrays list in trace_events.c" added taking the trace_types_lock mutex in trace_events.c as there were several locations that needed it for protection. Unfortunately, it also encapsulated a call to tracing_reset_all_online_cpus() which also takes the trace_types_lock, causing a deadlock. This happens when a module has tracepoints and has been traced. When the module is removed, the trace events module notifier will grab the trace_types_lock, do a bunch of clean ups, and also clears the buffer by calling tracing_reset_all_online_cpus. This doesn't happen often which explains why it wasn't caught right away. Commit a82274151af was marked for stable, which means this must be sent to stable too. Link: http://lkml.kernel.org/r/51EEC646.7070306@broadcom.com Reported-by: Arend van Spril <arend@broadcom.com> Tested-by: Arend van Spriel <arend@broadcom.com> Cc: Alexander Z Lam <azl@google.com> Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: David Sharp <dhsharp@google.com> Cc: stable@vger.kernel.org # 3.10 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24ftrace: Add check for NULL regs if ops has SAVE_REGS setSteven Rostedt (Red Hat)1-4/+14
If a ftrace ops is registered with the SAVE_REGS flag set, and there's already a ops registered to one of its functions but without the SAVE_REGS flag, there's a small race window where the SAVE_REGS ops gets added to the list of callbacks to call for that function before the callback trampoline gets set to save the regs. The problem is, the function is not currently saving regs, which opens a small race window where the ops that is expecting regs to be passed to it, wont. This can cause a crash if the callback were to reference the regs, as the SAVE_REGS guarantees that regs will be set. To fix this, we add a check in the loop case where it checks if the ops has the SAVE_REGS flag set, and if so, it will ignore it if regs is not set. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24tracing: Kill trace_cpu struct/membersOleg Nesterov2-29/+0
After the previous changes trace_array_cpu->trace_cpu and trace_array->trace_cpu becomes write-only. Remove these members and kill "struct trace_cpu" as well. As a side effect this also removes memset(per_cpu_memory, 0). It was not needed, alloc_percpu() returns zero-filled memory. Link: http://lkml.kernel.org/r/20130723152613.GA23741@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24tracing: Change tracing_fops/snapshot_fops to rely on tracing_get_cpu()Oleg Nesterov1-28/+22
tracing_open() and tracing_snapshot_open() are racy, the memory inode->i_private points to can be already freed. Convert these last users of "inode->i_private == trace_cpu" to use "i_private = trace_array" and rely on tracing_get_cpu(). v2: incorporate the fix from Steven, tracing_release() must not blindly dereference file->private_data unless we know that the file was opened for reading. Link: http://lkml.kernel.org/r/20130723152610.GA23737@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24tracing: Change tracing_entries_fops to rely on tracing_get_cpu()Oleg Nesterov1-37/+12
tracing_open_generic_tc() is racy, the memory inode->i_private points to can be already freed. 1. Change its last user, tracing_entries_fops, to use tracing_*_generic_tr() instead. 2. Change debugfs_create_file("buffer_size_kb", data) callers to pass "data = tr". 3. Change tracing_entries_read() and tracing_entries_write() to use tracing_get_cpu(). 4. Kill the no longer used tracing_open_generic_tc() and tracing_release_generic_tc(). Link: http://lkml.kernel.org/r/20130723152606.GA23730@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24tracing: Change tracing_stats_fops to rely on tracing_get_cpu()Oleg Nesterov1-7/+6
tracing_open_generic_tc() is racy, the memory inode->i_private points to can be already freed. 1. Change one of its users, tracing_stats_fops, to use tracing_*_generic_tr() instead. 2. Change trace_create_cpu_file("stats", data) to pass "data = tr". 3. Change tracing_stats_read() to use tracing_get_cpu(). Link: http://lkml.kernel.org/r/20130723152603.GA23727@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24tracing: Change tracing_buffers_fops to rely on tracing_get_cpu()Oleg Nesterov1-5/+4
tracing_buffers_open() is racy, the memory inode->i_private points to can be already freed. Change debugfs_create_file("trace_pipe_raw", data) caller to pass "data = tr", tracing_buffers_open() can use tracing_get_cpu(). Change debugfs_create_file("snapshot_raw_fops", data) caller too, this file uses tracing_buffers_open/release. Link: http://lkml.kernel.org/r/20130723152600.GA23720@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24tracing: Change tracing_pipe_fops() to rely on tracing_get_cpu()Oleg Nesterov1-9/+7
tracing_open_pipe() is racy, the memory inode->i_private points to can be already freed. Change debugfs_create_file("trace_pipe", data) callers to to pass "data = tr", tracing_open_pipe() can use tracing_get_cpu(). Link: http://lkml.kernel.org/r/20130723152557.GA23717@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24tracing: Introduce trace_create_cpu_file() and tracing_get_cpu()Oleg Nesterov1-14/+36
Every "file_operations" used by tracing_init_debugfs_percpu is buggy. f_op->open/etc does: 1. struct trace_cpu *tc = inode->i_private; struct trace_array *tr = tc->tr; 2. trace_array_get(tr) or fail; 3. do_something(tc); But tc (and tr) can be already freed before trace_array_get() is called. And it doesn't matter whether this file is per-cpu or it was created by init_tracer_debugfs(), free_percpu() or kfree() are equally bad. Note that even 1. is not safe, the freed memory can be unmapped. But even if it was safe trace_array_get() can wrongly succeed if we also race with the next new_instance_create() which can re-allocate the same tr, or tc was overwritten and ->tr points to the valid tr. In this case 3. uses the freed/reused memory. Add the new trivial helper, trace_create_cpu_file() which simply calls trace_create_file() and encodes "cpu" in "struct inode". Another helper, tracing_get_cpu() will be used to read cpu_nr-or-RING_BUFFER_ALL_CPUS. The patch abuses ->i_cdev to encode the number, it is never used unless the file is S_ISCHR(). But we could use something else, say, i_bytes or even ->d_fsdata. In any case this hack is hidden inside these 2 helpers, it would be trivial to change them if needed. This patch only changes tracing_init_debugfs_percpu() to use the new trace_create_cpu_file(), the next patches will change file_operations. Note: tracing_get_cpu(inode) is always safe but you can't trust the result unless trace_array_get() was called, without trace_types_lock which acts as a barrier it can wrongly return RING_BUFFER_ALL_CPUS. Link: http://lkml.kernel.org/r/20130723152554.GA23710@redhat.com Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-24Merge branch 'for-3.11-fixes' of ↵Linus Torvalds1-12/+19
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup changes from Tejun Heo: "This contains two patches, both of which aren't fixes per-se but I think it'd be better to fast-track them. One removes bcache_subsys_id which was added without proper review through the block tree. Fortunately, bcache cgroup code is unconditionally disabled, so this was never exposed to userland. The cgroup subsys_id is removed. Kent will remove the affected (disabled) code through bcache branch. The other simplifies task_group_path_from_hierarchy(). The function doesn't currently have in-kernel users but there are external code and development going on dependent on the function and making the function available for 3.11 would make things go smoother" * 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: replace task_cgroup_path_from_hierarchy() with task_cgroup_path() cgroup: remove bcache_subsys_id which got added stealthily
2013-07-24Fix __wait_on_atomic_t() to call the action func if the counter != 0David Howells1-1/+2
Fix __wait_on_atomic_t() so that it calls the action func if the counter != 0 rather than if the counter is 0 so as to be analogous to __wait_on_bit(). Thanks to Yacine who found this by visual inspection. This will affect FS-Cache in that it will could fail to sleep correctly when trying to clean up after a netfs cookie is withdrawn. Reported-by: Yacine Belkadi <yacine.belkadi.1@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: Milosz Tanski <milosz@adfin.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-23Merge tag 'trace-3.11-rc2' of ↵Linus Torvalds13-151/+166
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes and cleanups from Steven Rostedt: "This contains fixes, optimizations and some clean ups Some of the fixes need to go back to 3.10. They are minor, and deal mostly with incorrect ref counting in accessing event files. There was a couple of optimizations that should have perf perform a bit better when accessing trace events. And some various clean ups. Some of the clean ups are necessary to help in a fix to a theoretical race between opening a event file and deleting that event" * tag 'trace-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Kill the unbalanced tr->ref++ in tracing_buffers_open() tracing: Kill trace_array->waiter tracing: Do not (ab)use trace_seq in event_id_read() tracing: Simplify the iteration logic in f_start/f_next tracing: Add ref_data to function and fgraph tracer structs tracing: Miscellaneous fixes for trace_array ref counting tracing: Fix error handling to ensure instances can always be removed tracing/kprobe: Wait for disabling all running kprobe handlers tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare() tracing/syscall: Avoid perf_trace_buf_*() if sys_data->perf_events is empty tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is empty tracing: Typo fix on ring buffer comments tracing: Use trace_seq_puts()/trace_seq_putc() where possible tracing: Use correct config guard CONFIG_STACK_TRACER
2013-07-19tracing: Kill the unbalanced tr->ref++ in tracing_buffers_open()Oleg Nesterov1-2/+0
tracing_buffers_open() does trace_array_get() and then it wrongly inrcements tr->ref again under trace_types_lock. This means that every caller leaks trace_array: # cd /sys/kernel/debug/tracing/ # mkdir instances/X # true < instances/X/per_cpu/cpu0/trace_pipe_raw # rmdir instances/X rmdir: failed to remove `instances/X': Device or resource busy Link: http://lkml.kernel.org/r/20130719153644.GA18899@redhat.com Cc: Ingo Molnar <mingo@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: stable@vger.kernel.org # 3.10 Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19Merge tag 'pm+acpi-3.11-rc2' of ↵Linus Torvalds1-1/+2
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management and ACPI fixes from Rafael Wysocki: "These are fixes collected over the last week, most importnatly two cpufreq reverts fixing regressions introduced in 3.10, an autoseelp fix preventing systems using it from crashing during shutdown and two ACPI scan fixes related to hotplug. Specifics: - Two cpufreq commits from the 3.10 cycle introduced regressions. The first of them was buggy (it did way much more than it needed to do) and the second one attempted to fix an issue introduced by the first one. Fixes from Srivatsa S Bhat revert both. - If autosleep triggers during system shutdown and the shutdown callbacks of some device drivers have been called already, it may crash the system. Fix from Liu Shuo prevents that from happening by making try_to_suspend() check system_state. - The ACPI memory hotplug driver doesn't clear its driver_data on errors which may cause a NULL poiter dereference to happen later. Fix from Toshi Kani. - The ACPI namespace scanning code should not try to attach scan handlers to device objects that have them already, which may confuse things quite a bit, and it should rescan the whole namespace branch starting at the given node after receiving a bus check notify event even if the device at that particular node has been discovered already. Fixes from Rafael J Wysocki. - New ACPI video blacklist entry for a system whose initial backlight setting from the BIOS doesn't make sense. From Lan Tianyu. - Garbage string output avoindance for ACPI PNP from Liu Shuo. - Two Kconfig fixes for issues introduced recently in the s3c24xx cpufreq driver (when moving the driver to drivers/cpufreq) from Paul Bolle. - Trivial comment fix in pm_wakeup.h from Chanwoo Choi" * tag 'pm+acpi-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI / video: ignore BIOS initial backlight value for Fujitsu E753 PNP / ACPI: avoid garbage in resource name cpufreq: Revert commit 2f7021a8 to fix CPU hotplug regression cpufreq: s3c24xx: fix "depends on ARM_S3C24XX" in Kconfig cpufreq: s3c24xx: rename CONFIG_CPU_FREQ_S3C24XX_DEBUGFS PM / Sleep: Fix comment typo in pm_wakeup.h PM / Sleep: avoid 'autosleep' in shutdown progress cpufreq: Revert commit a66b2e to fix suspend/resume regression ACPI / memhotplug: Fix a stale pointer in error path ACPI / scan: Always call acpi_bus_scan() for bus check notifications ACPI / scan: Do not try to attach scan handlers to devices having them
2013-07-19tracing: Kill trace_array->waiterOleg Nesterov1-1/+0
Trivial. trace_array->waiter has no users since 6eaaa5d5 "tracing/core: use appropriate waiting on trace_pipe". Link: http://lkml.kernel.org/r/20130719142036.GA1594@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing: Do not (ab)use trace_seq in event_id_read()Oleg Nesterov1-13/+4
event_id_read() has no reason to kmalloc "struct trace_seq" (more than PAGE_SIZE!), it can use a small buffer instead. Note: "if (*ppos) return 0" looks strange and even wrong, simple_read_from_buffer() handles ppos != 0 case corrrectly. And it seems that almost every user of trace_seq in this file should be converted too. Unless you use seq_open(), trace_seq buys nothing compared to the raw buffer, but it needs a bit more memory and code. Link: http://lkml.kernel.org/r/20130718184712.GA4786@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing: Simplify the iteration logic in f_start/f_nextOleg Nesterov1-38/+22
f_next() looks overcomplicated, and it is not strictly correct even if this doesn't matter. Say, FORMAT_FIELD_SEPERATOR should not return NULL (means EOF) if trace_get_fields() returns an empty list, we should simply advance to FORMAT_PRINTFMT as we do when we find the end of list. 1. Change f_next() to return "struct list_head *" rather than "ftrace_event_field *", and change f_show() to do list_entry(). This simplifies the code a bit, only f_show() needs to know about ftrace_event_field, and f_next() can play with ->prev directly 2. Change f_next() to not play with ->prev / return inside the switch() statement. It can simply set node = head/common_head, the prev-or-advance-to-the-next-magic below does all work. While at it. f_start() looks overcomplicated too. I don't think *pos == 0 makes sense as a separate case, just change this code to do "while" instead of "do/while". The patch also moves f_start() down, close to f_stop(). This is purely cosmetic, just to make the locking added by the next patch more clear/visible. Link: http://lkml.kernel.org/r/20130718184710.GA4783@redhat.com Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing: Add ref_data to function and fgraph tracer structsSteven Rostedt (Red Hat)3-2/+11
The selftest for function and function graph tracers are defined as __init, as they are only executed at boot up. The "tracer" structs that are associated to those tracers are not setup as __init as they are used after boot. To stop mismatch warnings, those structures need to be annotated with __ref_data. Currently, the tracer structures are defined to __read_mostly, as they do not really change. But in the future they should be converted to consts, but that will take a little work because they have a "next" pointer that gets updated when they are registered. That will have to wait till the next major release. Link: http://lkml.kernel.org/r/1373596735.17876.84.camel@gandalf.local.home Reported-by: kbuild test robot <fengguang.wu@intel.com> Reported-by: Chen Gang <gang.chen@asianux.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing: Miscellaneous fixes for trace_array ref countingAlexander Z Lam2-8/+37
Some error paths did not handle ref counting properly, and some trace files need ref counting. Link: http://lkml.kernel.org/r/1374171524-11948-1-git-send-email-azl@google.com Cc: stable@vger.kernel.org # 3.10 Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: David Sharp <dhsharp@google.com> Cc: Alexander Z Lam <lambchop468@gmail.com> Signed-off-by: Alexander Z Lam <azl@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing: Fix error handling to ensure instances can always be removedAlexander Z Lam1-1/+3
Remove debugfs directories for tracing instances during creation if an error occurs causing the trace_array for that instance to not be added to ftrace_trace_arrays. If the directory continues to exist after the error, it cannot be removed because the respective trace_array is not in ftrace_trace_arrays. Link: http://lkml.kernel.org/r/1373502874-1706-2-git-send-email-azl@google.com Cc: stable@vger.kernel.org # 3.10 Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: David Sharp <dhsharp@google.com> Cc: Alexander Z Lam <lambchop468@gmail.com> Signed-off-by: Alexander Z Lam <azl@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing/kprobe: Wait for disabling all running kprobe handlersMasami Hiramatsu1-6/+17
Wait for disabling all running kprobe handlers when a kprobe event is disabled, since the caller, trace_remove_event_call() supposes that a removing event is disabled completely by disabling the event. With this change, ftrace can ensure that there is no running event handlers after disabling it. Link: http://lkml.kernel.org/r/20130709093526.20138.93100.stgit@mhiramat-M0-7522 Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare()Oleg Nesterov4-20/+4
Every perf_trace_buf_prepare() caller does WARN_ONCE(size > PERF_MAX_TRACE_SIZE, message) and "message" is almost the same. Shift this WARN_ONCE() into perf_trace_buf_prepare(). This changes the meaning of _ONCE, but I think this is fine. - 4947014 2932448 10104832 17984294 1126b26 vmlinux + 4948422 2932448 10104832 17985702 11270a6 vmlinux on my build. Link: http://lkml.kernel.org/r/20130617170211.GA19813@redhat.com Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing/syscall: Avoid perf_trace_buf_*() if sys_data->perf_events is emptyOleg Nesterov1-4/+8
perf_trace_buf_prepare() + perf_trace_buf_submit(head, task => NULL) make no sense if hlist_empty(head). Change perf_syscall_enter/exit() to check sys_data->{enter,exit}_event->perf_events beforehand. Link: http://lkml.kernel.org/r/20130617170207.GA19806@redhat.com Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is ↵Oleg Nesterov1-2/+4
empty perf_trace_buf_prepare() + perf_trace_buf_submit(head, task => NULL) make no sense if hlist_empty(head). Change perf_ftrace_function_call() to check event_function.perf_events beforehand. Link: http://lkml.kernel.org/r/20130617170204.GA19803@redhat.com Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing: Typo fix on ring buffer commentszhangwei(Jovi)1-7/+9
There have some mismatch between comments with real function name, update it. This patch also add some missed function arguments description. Link: http://lkml.kernel.org/r/51E3B3B2.4080307@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-19tracing: Use trace_seq_puts()/trace_seq_putc() where possiblezhangwei(Jovi)6-45/+45
For string without format specifiers, use trace_seq_puts() or trace_seq_putc(). Link: http://lkml.kernel.org/r/51E3B3AC.1000605@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> [ fixed a trace_seq_putc(s, " ") to trace_seq_putc(s, ' ') ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-18Merge tag 'driver-core-3.11-rc2' of ↵Linus Torvalds1-2/+0
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core patches from Greg KH: "Here are some driver core patches for 3.11-rc2. They aren't really bugfixes, but a bunch of new helper macros for drivers to properly create attribute groups, which drivers and subsystems need to fix up a ton of race issues with incorrectly creating sysfs files (binary and normal) after userspace has been told that the device is present. Also here is the ability to create binary files as attribute groups, to solve that race condition, which was impossible to do before this, so that's my fault the drivers were broken. The majority of the .c changes is indenting and moving code around a bit. It affects no existing code, but allows the large backlog of 70+ patches that I already have created to start flowing into the different subtrees, instead of having to live in my driver-core tree, causing merge nightmares in linux-next for the next few months. These were finalized too late for the -rc1 merge window, which is why they were didn't make that pull request, testing and review from others didn't happen until a few weeks ago, and then there's the whole distraction of the past few days, which prevented these from getting to you sooner, sorry about that. Oh, and there's a bugfix for the documentation build warning in here as well. All of these have been in linux-next this week, with no reported problems" * tag 'driver-core-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: driver-core: fix new kernel-doc warning in base/platform.c sysfs: use file mode defines from stat.h sysfs: add more helper macro's for (bin_)attribute(_groups) driver core: add default groups to struct class driver core: Introduce device_create_groups sysfs: prevent warning when only using binary attributes sysfs: add support for binary attributes in groups driver core: device.h: add RW and RO attribute macros sysfs.h: add BIN_ATTR macro sysfs.h: add ATTRIBUTE_GROUPS() macro sysfs.h: add __ATTR_RW() macro
2013-07-16sysfs.h: add __ATTR_RW() macroGreg Kroah-Hartman1-2/+0
A number of parts of the kernel created their own version of this, might as well have the sysfs core provide it instead. Reviewed-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-07-15tracing: Use correct config guard CONFIG_STACK_TRACERzhangwei(Jovi)1-2/+2
We should use CONFIG_STACK_TRACER to guard readme text of stack tracer related file, not CONFIG_STACKTRACE. Link: http://lkml.kernel.org/r/51E3B3A2.8080609@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-07-15kernel: delete __cpuinit usage from all core kernel filesPaul Gortmaker15-33/+33
The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the uses of the __cpuinit macros from C files in the core kernel directories (kernel, init, lib, mm, and include) that don't really have a specific maintainer. [1] https://lkml.org/lkml/2013/5/20/589 Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-15rcu: delete __cpuinit usage from all rcu filesPaul Gortmaker4-11/+11
The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the drivers/rcu uses of the __cpuinit macros from all C files. [1] https://lkml.org/lkml/2013/5/20/589 Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@freedesktop.org> Cc: Dipankar Sarma <dipankar@in.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-15PM / Sleep: avoid 'autosleep' in shutdown progressLiu ShuoX1-1/+2
Prevent automatic system suspend from happening during system shutdown by making try_to_suspend() check system_state and return immediately if it is not SYSTEM_RUNNING. This prevents the following breakage from happening (scenario from Zhang Yanmin): Kernel starts shutdown and calls all device driver's shutdown callback. When a driver's shutdown is called, the last wakelock is released and suspend-to-ram starts. However, as some driver's shut down callbacks already shut down devices and disabled runtime pm, the suspend-to-ram calls driver's suspend callback without noticing that device is already off and causes crash. [rjw: Changelog] Signed-off-by: Liu ShuoX <shuox.liu@intel.com> Cc: 3.5+ <stable@vger.kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-07-14Merge branch 'for-linus' of ↵Linus Torvalds1-10/+1
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull more vfs stuff from Al Viro: "O_TMPFILE ABI changes, Oleg's fput() series, misc cleanups, including making simple_lookup() usable for filesystems with non-NULL s_d_op, which allows us to get rid of quite a bit of ugliness" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: sunrpc: now we can just set ->s_d_op cgroup: we can use simple_lookup() now efivarfs: we can use simple_lookup() now make simple_lookup() usable for filesystems that set ->s_d_op configfs: don't open-code d_alloc_name() __rpc_lookup_create_exclusive: pass string instead of qstr rpc_create_*_dir: don't bother with qstr llist: llist_add() can use llist_add_batch() llist: fix/simplify llist_add() and llist_add_batch() fput: turn "list_head delayed_fput_list" into llist_head fs/file_table.c:fput(): add comment Safer ABI for O_TMPFILE
2013-07-14cgroup: we can use simple_lookup() nowAl Viro1-10/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-14Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds1-9/+11
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fix from Thomas Gleixner: "Fix a potential deadlock versus hrtimers" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix HRTICK
2013-07-14Merge branch 'irq-urgent-for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull irq updates from Thomas Gleixner: - core fix for missing round up in the generic irq chip implementation - new irq chip for MOXA SoCs - a few fixes and cleanups in the irqchip drivers * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: irqchip: Add support for MOXA ART SoCs genirq: generic chip: Use DIV_ROUND_UP to calculate numchips irqchip: nvic: Fix wrong num_ct argument for irq_alloc_domain_generic_chips() irqchip: sun4i: Staticize sun4i_irq_ack() irqchip: vt8500: Staticize local symbols
2013-07-14Merge branch 'timers-urgent-for-linus' of ↵Linus Torvalds4-62/+75
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer updates from Thomas Gleixner: - watchdog fixes for full dynticks - improved debug output for full dynticks - remove an obsolete full dynticks check - two ARM SoC clocksource drivers for sharing across SoCs - tick broadcast fix for CPU hotplug * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tick: broadcast: Check broadcast mode on CPU hotplug clocksource: arm_global_timer: Add ARM global timer support clocksource: Add Marvell Orion SoC timer nohz: Remove obsolete check for full dynticks CPUs to be RCU nocbs watchdog: Boot-disable by default on full dynticks watchdog: Rename confusing state variable watchdog: Register / unregister watchdog kthreads on sysctl control nohz: Warn if the machine can not perform nohz_full
2013-07-14Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds1-3/+25
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Thomas Gleixner: - fix for do_div() abuse on x86 - locking fix in perf core - a pile of (build) fixes and cleanups in perf tools * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) perf/x86: Fix incorrect use of do_div() in NMI warning perf: Fix perf_lock_task_context() vs RCU perf: Remove WARN_ON_ONCE() check in __perf_event_enable() for valid scenario perf: Clone child context from parent context pmu perf script: Fix broken include in Context.xs perf tools: Fix -ldw/-lelf link test when static linking perf tools: Revert regression in configuration of Python support perf tools: Fix perf version generation perf stat: Fix per-socket output bug for uncore events perf symbols: Fix vdso list searching perf evsel: Fix missing increment in sample parsing perf tools: Update symbol_conf.nr_events when processing attribute events perf tools: Fix new_term() missing free on error path perf tools: Fix parse_events_terms() segfault on error path perf evsel: Fix count parameter to read call in event_format__new perf tools: fix a typo of a Power7 event name perf tools: Fix -x/--exclude-other option for report command perf evlist: Enhance perf_evlist__start_workload() perf record: Remove -f/--force option perf record: Remove -A/--append option ...
2013-07-14Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core locking updates from Thomas Gleixner: "Header cleanup as requested by Linus" (This is the "don't include support for ww_mutex in a header file that everybody wants, when almost nobody wants the ww part" change) * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: mutex: Move ww_mutex definitions to ww_mutex.h
2013-07-14Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linusLinus Torvalds1-12/+0
Pull MIPS updates from Ralf Baechle: "MIPS updates: - All the things that didn't make 3.10. - Removes the Windriver PPMC platform. Nobody will miss it. - Remove a workaround from kernel/irq/irqdomain.c which was there exclusivly for MIPS. Patch by Grant Likely. - More small improvments for the SEAD 3 platform - Improvments on the BMIPS / SMP support for the BCM63xx series. - Various cleanups of dead leftovers. - Platform support for the Cavium Octeon-based EdgeRouter Lite. Two large KVM patchsets didn't make it for this pull request because their respective authors are vacationing" * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (124 commits) MIPS: Kconfig: Add missing MODULES dependency to VPE_LOADER MIPS: BCM63xx: CLK: Add dummy clk_{set,round}_rate() functions MIPS: SEAD3: Disable L2 cache on SEAD-3. MIPS: BCM63xx: Enable second core SMP on BCM6328 if available MIPS: BCM63xx: Add SMP support to prom.c MIPS: define write{b,w,l,q}_relaxed MIPS: Expose missing pci_io{map,unmap} declarations MIPS: Malta: Update GCMP detection. Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET" MIPS: APSP: Remove <asm/kspd.h> SSB: Kconfig: Amend SSB_EMBEDDED dependencies MIPS: microMIPS: Fix improper definition of ISA exception bit. MIPS: Don't try to decode microMIPS branch instructions where they cannot exist. MIPS: Declare emulate_load_store_microMIPS as a static function. MIPS: Fix typos and cleanup comment MIPS: Cleanup indentation and whitespace MIPS: BMIPS: support booting from physical CPU other than 0 MIPS: Only set cpu_has_mmips if SYS_SUPPORTS_MICROMIPS MIPS: GIC: Fix gic_set_affinity infinite loop MIPS: Don't save/restore OCTEON wide multiplier state on syscalls. ...
2013-07-12cgroup: replace task_cgroup_path_from_hierarchy() with task_cgroup_path()Tejun Heo1-12/+19
task_cgroup_path_from_hierarchy() was added for the planned new users and none of the currently planned users wants to know about multiple hierarchies. This patch drops the multiple hierarchy part and makes it always return the path in the first non-dummy hierarchy. As unified hierarchy will always have id 1, this is guaranteed to return the path for the unified hierarchy if mounted; otherwise, it will return the path from the hierarchy which happens to occupy the lowest hierarchy id, which will usually be the first hierarchy mounted after boot. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kaluža <jkaluza@redhat.com>
2013-07-12sched: Fix HRTICKPeter Zijlstra1-9/+11
David reported that the HRTICK sched feature was borken; which was enough motivation for me to finally fix it ;-) We should not allow hrtimer code to do softirq wakeups while holding scheduler locks. The hrtimer code only needs this when we accidentally try to program an expired time. We don't much care about those anyway since we have the regular tick to fall back to. Reported-by: David Ahern <dsahern@gmail.com> Tested-by: David Ahern <dsahern@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130628091853.GE29209@dyad.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-12tick: broadcast: Check broadcast mode on CPU hotplugStephen Boyd1-1/+4
On ARM systems the dummy clockevent is registered with the cpu hotplug notifier chain before any other per-cpu clockevent. This has the side-effect of causing the dummy clockevent to be registered first in every hotplug sequence. Because the dummy is first, we'll try to turn the broadcast source on but the code in tick_device_uses_broadcast() assumes the broadcast source is in periodic mode and calls tick_broadcast_start_periodic() unconditionally. On boot this isn't a problem because we typically haven't switched into oneshot mode yet (if at all). During hotplug, if the broadcast source isn't in periodic mode we'll replace the broadcast oneshot handler with the broadcast periodic handler and start emulating oneshot mode when we shouldn't. Due to the way the broadcast oneshot handler programs the next_event it's possible for it to contain KTIME_MAX and cause us to hang the system when the periodic handler tries to program the next tick. Fix this by using the appropriate function to start the broadcast source. Reported-by: Stephen Warren <swarren@nvidia.com> Tested-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Mark Rutland <Mark.Rutland@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: ARM kernel mailing list <linux-arm-kernel@lists.infradead.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Joseph Lo <josephl@nvidia.com> Link: http://lkml.kernel.org/r/20130711140059.GA27430@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-07-12Merge branch 'linus' into timers/urgentThomas Gleixner62-2553/+3927
Get upstream changes so we can apply fixes against them Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-07-12mutex: Move ww_mutex definitions to ww_mutex.hMaarten Lankhorst1-0/+1
Move the definitions for wound/wait mutexes out to a separate header, ww_mutex.h. This reduces clutter in mutex.h, and increases readability. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Cc: Dave Airlie <airlied@gmail.com> Link: http://lkml.kernel.org/r/51D675DC.3000907@canonical.com [ Tidied up the code a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-12perf: Fix perf_lock_task_context() vs RCUPeter Zijlstra1-1/+14
Jiri managed to trigger this warning: [] ====================================================== [] [ INFO: possible circular locking dependency detected ] [] 3.10.0+ #228 Tainted: G W [] ------------------------------------------------------- [] p/6613 is trying to acquire lock: [] (rcu_node_0){..-...}, at: [<ffffffff810ca797>] rcu_read_unlock_special+0xa7/0x250 [] [] but task is already holding lock: [] (&ctx->lock){-.-...}, at: [<ffffffff810f2879>] perf_lock_task_context+0xd9/0x2c0 [] [] which lock already depends on the new lock. [] [] the existing dependency chain (in reverse order) is: [] [] -> #4 (&ctx->lock){-.-...}: [] -> #3 (&rq->lock){-.-.-.}: [] -> #2 (&p->pi_lock){-.-.-.}: [] -> #1 (&rnp->nocb_gp_wq[1]){......}: [] -> #0 (rcu_node_0){..-...}: Paul was quick to explain that due to preemptible RCU we cannot call rcu_read_unlock() while holding scheduler (or nested) locks when part of the read side critical section was preemptible. Therefore solve it by making the entire RCU read side non-preemptible. Also pull out the retry from under the non-preempt to play nice with RT. Reported-by: Jiri Olsa <jolsa@redhat.com> Helped-out-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-12perf: Remove WARN_ON_ONCE() check in __perf_event_enable() for valid scenarioJiri Olsa1-1/+10
The '!ctx->is_active' check has a valid scenario, so there's no need for the warning. The reason is that there's a time window between the 'ctx->is_active' check in the perf_event_enable() function and the __perf_event_enable() function having: - IRQs on - ctx->lock unlocked where the task could be killed and 'ctx' deactivated by perf_event_exit_task(), ending up with the warning below. So remove the WARN_ON_ONCE() check and add comments to explain it all. This addresses the following warning reported by Vince Weaver: [ 324.983534] ------------[ cut here ]------------ [ 324.984420] WARNING: at kernel/events/core.c:1953 __perf_event_enable+0x187/0x190() [ 324.984420] Modules linked in: [ 324.984420] CPU: 19 PID: 2715 Comm: nmi_bug_snb Not tainted 3.10.0+ #246 [ 324.984420] Hardware name: Supermicro X8DTN/X8DTN, BIOS 4.6.3 01/08/2010 [ 324.984420] 0000000000000009 ffff88043fce3ec8 ffffffff8160ea0b ffff88043fce3f00 [ 324.984420] ffffffff81080ff0 ffff8802314fdc00 ffff880231a8f800 ffff88043fcf7860 [ 324.984420] 0000000000000286 ffff880231a8f800 ffff88043fce3f10 ffffffff8108103a [ 324.984420] Call Trace: [ 324.984420] <IRQ> [<ffffffff8160ea0b>] dump_stack+0x19/0x1b [ 324.984420] [<ffffffff81080ff0>] warn_slowpath_common+0x70/0xa0 [ 324.984420] [<ffffffff8108103a>] warn_slowpath_null+0x1a/0x20 [ 324.984420] [<ffffffff81134437>] __perf_event_enable+0x187/0x190 [ 324.984420] [<ffffffff81130030>] remote_function+0x40/0x50 [ 324.984420] [<ffffffff810e51de>] generic_smp_call_function_single_interrupt+0xbe/0x130 [ 324.984420] [<ffffffff81066a47>] smp_call_function_single_interrupt+0x27/0x40 [ 324.984420] [<ffffffff8161fd2f>] call_function_single_interrupt+0x6f/0x80 [ 324.984420] <EOI> [<ffffffff816161a1>] ? _raw_spin_unlock_irqrestore+0x41/0x70 [ 324.984420] [<ffffffff8113799d>] perf_event_exit_task+0x14d/0x210 [ 324.984420] [<ffffffff810acd04>] ? switch_task_namespaces+0x24/0x60 [ 324.984420] [<ffffffff81086946>] do_exit+0x2b6/0xa40 [ 324.984420] [<ffffffff8161615c>] ? _raw_spin_unlock_irq+0x2c/0x30 [ 324.984420] [<ffffffff81087279>] do_group_exit+0x49/0xc0 [ 324.984420] [<ffffffff81096854>] get_signal_to_deliver+0x254/0x620 [ 324.984420] [<ffffffff81043057>] do_signal+0x57/0x5a0 [ 324.984420] [<ffffffff8161a164>] ? __do_page_fault+0x2a4/0x4e0 [ 324.984420] [<ffffffff8161665c>] ? retint_restore_args+0xe/0xe [ 324.984420] [<ffffffff816166cd>] ? retint_signal+0x11/0x84 [ 324.984420] [<ffffffff81043605>] do_notify_resume+0x65/0x80 [ 324.984420] [<ffffffff81616702>] retint_signal+0x46/0x84 [ 324.984420] ---[ end trace 442ec2f04db3771a ]--- Reported-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Jiri Olsa <jolsa@redhat.com> Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1373384651-6109-2-git-send-email-jolsa@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>