kernel/linux.git/drivers/oprofile/buffer_sync.c, branch linux-2.6.35.y

oprofile: fix crash when accessing freed task structs

2010-09-20T20:36:29+00:00

commit 750d857c682f4db60d14722d430c7ccc35070962 upstream. This patch fixes a crash during shutdown reported below. The crash is caused by accessing already freed task structs. The fix changes the order for registering and unregistering notifier callbacks. All notifiers must be initialized before buffers start working. To stop buffer synchronization we cancel all workqueues, unregister the notifier callback and then flush all buffers. After all of this we finally can free all tasks listed. This should avoid accessing freed tasks. On 22.07.10 01:14:40, Benjamin Herrenschmidt wrote: > So the initial observation is a spinlock bad magic followed by a crash > in the spinlock debug code: > > [ 1541.586531] BUG: spinlock bad magic on CPU#5, events/5/136 > [ 1541.597564] Unable to handle kernel paging request for data at address 0x6b6b6b6b6b6b6d03 > > Backtrace looks like: > > spin_bug+0x74/0xd4 > ._raw_spin_lock+0x48/0x184 > ._spin_lock+0x10/0x24 > .get_task_mm+0x28/0x8c > .sync_buffer+0x1b4/0x598 > .wq_sync_buffer+0xa0/0xdc > .worker_thread+0x1d8/0x2a8 > .kthread+0xa8/0xb4 > .kernel_thread+0x54/0x70 > > So we are accessing a freed task struct in the work queue when > processing the samples. Reported-by: Benjamin Herrenschmidt Signed-off-by: Robert Richter Signed-off-by: Greg Kroah-Hartman

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30T13:02:32+00:00

percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo Guess-its-ok-by: Christoph Lameter Cc: Ingo Molnar Cc: Lee Schermerhorn

cpumask: use zalloc_cpumask_var() where possible

2009-09-24T00:04:24+00:00

Remove open-coded zalloc_cpumask_var() and zalloc_cpumask_var_node(). Signed-off-by: Li Zefan Signed-off-by: Rusty Russell

cpumask: modifiy oprofile initialization

2009-01-22T13:37:06+00:00

Delta patch to f7df8ed164996cd2c6aca9674388be6ef78d8b37 for tip/cpus4096. Moved initialization to sync_start()/sync_stop(). No changes needed in buffer_sync.h and oprof.c anymore. Signed-off-by: Robert Richter Signed-off-by: Ingo Molnar

cpumask: convert misc driver functions

2009-01-11T18:12:52+00:00

Impact: use new cpumask API. Convert misc driver functions to use struct cpumask. To Do: - Convert iucv_buffer_cpumask to cpumask_var_t. Signed-off-by: Rusty Russell Signed-off-by: Mike Travis Acked-by: Dean Nelson Cc: Robert Richter Cc: oprofile-list@lists.sf.net Cc: Jeremy Fitzhardinge Cc: Chris Wright Cc: virtualization@lists.osdl.org Cc: xen-devel@lists.xensource.com Cc: Ursula Braun Cc: linux390@de.ibm.com Cc: linux-s390@vger.kernel.org

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile

2009-01-09T20:43:06+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile: (31 commits) powerpc/oprofile: fix whitespaces in op_model_cell.c powerpc/oprofile: IBM CELL: add SPU event profiling support powerpc/oprofile: fix cell/pr_util.h powerpc/oprofile: IBM CELL: cleanup and restructuring oprofile: make new cpu buffer functions part of the api oprofile: remove #ifdef CONFIG_OPROFILE_IBS in non-ibs code ring_buffer: fix ring_buffer_event_length() oprofile: use new data sample format for ibs oprofile: add op_cpu_buffer_get_data() oprofile: add op_cpu_buffer_add_data() oprofile: rework implementation of cpu buffer events oprofile: modify op_cpu_buffer_read_entry() oprofile: add op_cpu_buffer_write_reserve() oprofile: rename variables in add_ibs_begin() oprofile: rename add_sample() in cpu_buffer.c oprofile: rename variable ibs_allowed to has_ibs in op_model_amd.c oprofile: making add_sample_entry() inline oprofile: remove backtrace code for ibs oprofile: remove unused ibs macro oprofile: remove unused components in struct oprofile_cpu_buffer ...

oprofile: remove #ifdef CONFIG_OPROFILE_IBS in non-ibs code

2009-01-07T21:47:56+00:00

The ifdefs can be removed since the code is no longer ibs specific and can be used for other purposes as well. IBS specific code is only in op_model_amd.c. Signed-off-by: Robert Richter

oprofile: use new data sample format for ibs

2009-01-07T21:47:23+00:00

The new ring buffer implementation allows the storage of samples with different size. This patch implements the usage of the new sample format to store ibs samples in the cpu buffer. Until now, writing to the cpu buffer could lead to incomplete sampling sequences since IBS samples were transfered in multiple samples. Due to a full buffer, data could be lost at any time. This can't happen any more since the complete data is reserved in advance and then stored in a single sample. Signed-off-by: Robert Richter

oprofile: add op_cpu_buffer_get_data()

2009-01-07T21:45:46+00:00

This function provides access to attached data of a sample. It returns the size of data including the current value. Also, op_cpu_buffer_get_size() is available to check if there is data attached. Signed-off-by: Robert Richter

oprofile: rework implementation of cpu buffer events

2009-01-07T21:40:47+00:00

Special events such as task or context switches are marked with an escape code in the cpu buffer followed by an event code or a task identifier. There is one escape code per event. To make escape sequences also available for data samples the internal cpu buffer format must be changed. The current implementation does not allow the extension of event codes since this would lead to collisions with the task identifiers. To avoid this, this patch introduces an event mask that allows the storage of multiple events with one escape code. Now, task identifiers are stored in the data section of the sample. The implementation also allows the usage of custom data in a sample. As a side effect the new code is much more readable and easier to understand. Signed-off-by: Robert Richter