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2021-03-30kernel/printk.c: Fixed mundane typosBhaskar Chowdhury1-3/+3
s/sempahore/semaphore/ s/exacly/exactly/ s/unregistred/unregistered/ s/interation/iteration/ Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com> Reviewed-by: Petr Mladek <pmladek@suse.com> [pmladek@suse.com: Removed 4th hunk. The string has already been removed in the meantime.] Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210328043932.8310-1-unixbhaskar@gmail.com
2021-03-30printk: rename vprintk_func to vprintkRasmus Villemoes3-11/+3
The printk code is already hard enough to understand. Remove an unnecessary indirection by renaming vprintk_func to vprintk (adding the asmlinkage annotation), and removing the vprintk definition from printk.c. That way, printk is implemented in terms of vprintk as one would expect, and there's no "vprintk_func, what's that? Some function pointer that gets set where?" The declaration of vprintk in linux/printk.h already has the __printf(1,0) attribute, there's no point repeating that with the definition - it's for diagnostics in callers. linux/printk.h already contains a static inline {return 0;} definition of vprintk when !CONFIG_PRINTK. Since the corresponding stub definition of vprintk_func was not marked "static inline", any translation unit including internal.h would get a definition of vprintk_func - it just so happens that for !CONFIG_PRINTK, there is precisely one such TU, namely printk.c. Had there been more, it would be a link error; now it's just a silly waste of a few bytes of .text, which one must assume are rather precious to anyone disabling PRINTK. $ objdump -dr kernel/printk/printk.o 00000330 <vprintk_func>: 330: 31 c0 xor %eax,%eax 332: c3 ret 333: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi 33a: 8d b6 00 00 00 00 lea 0x0(%esi),%esi Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210323144201.486050-1-linux@rasmusvillemoes.dk
2021-03-08printk: console: remove unnecessary safe buffer usageJohn Ogness1-7/+3
Upon registering a console, safe buffers are activated when setting up the sequence number to replay the log. However, these are already protected by @console_sem and @syslog_lock. Remove the unnecessary safe buffer usage. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-16-john.ogness@linutronix.de
2021-03-08printk: kmsg_dump: remove _nolock() variantsJohn Ogness1-52/+8
kmsg_dump_rewind() and kmsg_dump_get_line() are lockless, so there is no need for _nolock() variants. Remove these functions and switch all callers of the _nolock() variants. The functions without _nolock() were chosen because they are already exported to kernel modules. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-15-john.ogness@linutronix.de
2021-03-08printk: remove logbuf_lockJohn Ogness3-97/+46
Since the ringbuffer is lockless, there is no need for it to be protected by @logbuf_lock. Remove @logbuf_lock. @console_seq, @exclusive_console_stop_seq, @console_dropped are protected by @console_lock. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-14-john.ogness@linutronix.de
2021-03-08printk: introduce a kmsg_dump iteratorJohn Ogness1-31/+32
Rather than storing the iterator information in the registered kmsg_dumper structure, create a separate iterator structure. The kmsg_dump_iter structure can reside on the stack of the caller, thus allowing lockless use of the kmsg_dump functions. Update code that accesses the kernel logs using the kmsg_dumper structure to use the new kmsg_dump_iter structure. For kmsg_dumpers, this also means adding a call to kmsg_dump_rewind() to initialize the iterator. All this is in preparation for removal of @logbuf_lock. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Kees Cook <keescook@chromium.org> # pstore Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-13-john.ogness@linutronix.de
2021-03-08printk: kmsg_dumper: remove @active fieldJohn Ogness1-9/+1
All 6 kmsg_dumpers do not benefit from the @active flag: (provide their own synchronization) - arch/powerpc/kernel/nvram_64.c - arch/um/kernel/kmsg_dump.c - drivers/mtd/mtdoops.c - fs/pstore/platform.c (only dump on KMSG_DUMP_PANIC, which does not require synchronization) - arch/powerpc/platforms/powernv/opal-kmsg.c - drivers/hv/vmbus_drv.c The other 2 kmsg_dump users also do not rely on @active: (hard-code @active to always be true) - arch/powerpc/xmon/xmon.c - kernel/debug/kdb/kdb_main.c Therefore, @active can be removed. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-12-john.ogness@linutronix.de
2021-03-08printk: add syslog_lockJohn Ogness1-4/+37
The global variables @syslog_seq, @syslog_partial, @syslog_time and write access to @clear_seq are protected by @logbuf_lock. Once @logbuf_lock is removed, these variables will need their own synchronization method. Introduce @syslog_lock for this purpose. @syslog_lock is a raw_spin_lock for now. This simplifies the transition to removing @logbuf_lock. Once @logbuf_lock and the safe buffers are removed, @syslog_lock can change to spin_lock. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-11-john.ogness@linutronix.de
2021-03-08printk: use atomic64_t for devkmsg_user.seqJohn Ogness1-12/+12
@user->seq is indirectly protected by @logbuf_lock. Once @logbuf_lock is removed, @user->seq will be no longer safe from an atomicity point of view. In preparation for the removal of @logbuf_lock, change it to atomic64_t to provide this safety. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-10-john.ogness@linutronix.de
2021-03-08printk: use seqcount_latch for clear_seqJohn Ogness1-8/+50
kmsg_dump_rewind_nolock() locklessly reads @clear_seq. However, this is not done atomically. Since @clear_seq is 64-bit, this cannot be an atomic operation for all platforms. Therefore, use a seqcount_latch to allow readers to always read a consistent value. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-9-john.ogness@linutronix.de
2021-03-08printk: introduce CONSOLE_LOG_MAXJohn Ogness1-8/+12
Instead of using "LOG_LINE_MAX + PREFIX_MAX" for temporary buffer sizes, introduce CONSOLE_LOG_MAX. This represents the maximum size that is allowed to be printed to the console for a single record. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-8-john.ogness@linutronix.de
2021-03-08printk: consolidate kmsg_dump_get_buffer/syslog_print_all codeJohn Ogness1-37/+50
The logic for finding records to fit into a buffer is the same for kmsg_dump_get_buffer() and syslog_print_all(). Introduce a helper function find_first_fitting_seq() to handle this logic. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-7-john.ogness@linutronix.de
2021-03-08printk: refactor kmsg_dump_get_buffer()John Ogness1-29/+33
kmsg_dump_get_buffer() requires nearly the same logic as syslog_print_all(), but uses different variable names and does not make use of the ringbuffer loop macros. Modify kmsg_dump_get_buffer() so that the implementation is as similar to syslog_print_all() as possible. A follow-up commit will move this common logic into a separate helper function. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-6-john.ogness@linutronix.de
2021-03-08printk: limit second loop of syslog_print_allJohn Ogness1-1/+8
The second loop of syslog_print_all() subtracts lengths that were added in the first loop. With commit b031a684bfd0 ("printk: remove logbuf_lock writer-protection of ringbuffer") it is possible that records are (over)written during syslog_print_all(). This allows the possibility of the second loop subtracting lengths that were never added in the first loop. This situation can result in syslog_print_all() filling the buffer starting from a later record, even though there may have been room to fit the earlier record(s) as well. Fixes: b031a684bfd0 ("printk: remove logbuf_lock writer-protection of ringbuffer") Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210303101528.29901-4-john.ogness@linutronix.de
2021-02-22Merge branch 'printk-rework' into for-linusPetr Mladek2-11/+19
2021-02-12printk: avoid prb_first_valid_seq() where possibleJohn Ogness1-10/+18
If message sizes average larger than expected (more than 32 characters), the data_ring will wrap before the desc_ring. Once the data_ring wraps, it will start invalidating descriptors. These invalid descriptors hang around until they are eventually recycled when the desc_ring wraps. Readers do not care about invalid descriptors, but they still need to iterate past them. If the average message size is much larger than 32 characters, then there will be many invalid descriptors preceding the valid descriptors. The function prb_first_valid_seq() always begins at the oldest descriptor and searches for the first valid descriptor. This can be rather expensive for the above scenario. And, in fact, because of its heavy usage in /dev/kmsg, there have been reports of long delays and even RCU stalls. For code that does not need to search from the oldest record, replace prb_first_valid_seq() usage with prb_read_valid_*() functions, which provide a start sequence number to search from. Fixes: 896fbe20b4e2333fb55 ("printk: use the lockless ringbuffer") Reported-by: kernel test robot <oliver.sang@intel.com> Reported-by: J. Avila <elavila@google.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210211173152.1629-1-john.ogness@linutronix.de
2021-02-10printk: fix deadlock when kernel panicMuchun Song1-4/+12
printk_safe_flush_on_panic() caused the following deadlock on our server: CPU0: CPU1: panic rcu_dump_cpu_stacks kdump_nmi_shootdown_cpus nmi_trigger_cpumask_backtrace register_nmi_handler(crash_nmi_callback) printk_safe_flush __printk_safe_flush raw_spin_lock_irqsave(&read_lock) // send NMI to other processors apic_send_IPI_allbutself(NMI_VECTOR) // NMI interrupt, dead loop crash_nmi_callback printk_safe_flush_on_panic printk_safe_flush __printk_safe_flush // deadlock raw_spin_lock_irqsave(&read_lock) DEADLOCK: read_lock is taken on CPU1 and will never get released. It happens when panic() stops a CPU by NMI while it has been in the middle of printk_safe_flush(). Handle the lock the same way as logbuf_lock. The printk_safe buffers are flushed only when both locks can be safely taken. It can avoid the deadlock _in this particular case_ at expense of losing contents of printk_safe buffers. Note: It would actually be safe to re-init the locks when all CPUs were stopped by NMI. But it would require passing this information from arch-specific code. It is not worth the complexity. Especially because logbuf_lock and printk_safe buffers have been obsoleted by the lockless ring buffer. Fixes: cf9b1106c81c ("printk/nmi: flush NMI messages on the system panic") Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: <stable@vger.kernel.org> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210210034823.64867-1-songmuchun@bytedance.com
2021-01-26printk: rectify kernel-doc for prb_rec_init_wr()Lukas Bulwahn1-1/+1
The command 'find ./kernel/printk/ | xargs ./scripts/kernel-doc -none' reported a mismatch with the kernel-doc of prb_rec_init_wr(). Rectify the kernel-doc, such that no issues remain for ./kernel/printk/. Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210125081748.19903-1-lukas.bulwahn@gmail.com
2021-01-25Merge branch 'printk-rework' into for-linusPetr Mladek1-1/+1
2021-01-25printk: fix string termination for record_print_text()John Ogness1-1/+1
Commit f0e386ee0c0b ("printk: fix buffer overflow potential for print_text()") added string termination in record_print_text(). However it used the wrong base pointer for adding the terminator. This led to a 0-byte being written somewhere beyond the buffer. Use the correct base pointer when adding the terminator. Fixes: f0e386ee0c0b ("printk: fix buffer overflow potential for print_text()") Reported-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210124202728.4718-1-john.ogness@linutronix.de
2021-01-21Merge branch 'printk-rework' into for-linusPetr Mladek2-12/+30
2021-01-19printk: fix buffer overflow potential for print_text()John Ogness1-9/+27
Before the commit 896fbe20b4e2333fb55 ("printk: use the lockless ringbuffer"), msg_print_text() would only write up to size-1 bytes into the provided buffer. Some callers expect this behavior and append a terminator to returned string. In particular: arch/powerpc/xmon/xmon.c:dump_log_buf() arch/um/kernel/kmsg_dump.c:kmsg_dumper_stdout() msg_print_text() has been replaced by record_print_text(), which currently fills the full size of the buffer. This causes a buffer overflow for the above callers. Change record_print_text() so that it will only use size-1 bytes for text data. Also, for paranoia sakes, add a terminator after the text data. And finally, document this behavior so that it is clear that only size-1 bytes are used and a terminator is added. Fixes: 896fbe20b4e2333fb55 ("printk: use the lockless ringbuffer") Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210114170412.4819-1-john.ogness@linutronix.de
2021-01-15printk: fix kmsg_dump_get_buffer length calulationsJohn Ogness1-2/+2
kmsg_dump_get_buffer() uses @syslog to determine if the syslog prefix should be written to the buffer. However, when calculating the maximum number of records that can fit into the buffer, it always counts the bytes from the syslog prefix. Use @syslog when calculating the maximum number of records that can fit into the buffer. Fixes: e2ae715d66bf ("kmsg - kmsg_dump() use iterator to receive log buffer content") Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210113164413.1599-1-john.ogness@linutronix.de
2021-01-15printk: ringbuffer: fix line countingJohn Ogness1-1/+1
Counting text lines in a record simply involves counting the number of newline characters (+1). However, it is searching the full data block for newline characters, even though the text data can be (and often is) a subset of that area. Since the extra area in the data block was never initialized, the result is that extra newlines may be seen and counted. Restrict newline searching to the text data length. Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer") Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210113144234.6545-1-john.ogness@linutronix.de
2020-12-16Merge tag 'printk-for-5.11' of ↵Linus Torvalds2-119/+170
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Finally allow parallel writes and reads into/from the lockless ringbuffer. But it is not a complete solution. Readers are still serialized against each other. And nested writes are still prevented by printk_safe per-CPU buffers. - Use ttynull as the ultimate fallback for /dev/console. - Officially allow disabling console output by using console="" or console=null - A few code cleanups * tag 'printk-for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: remove logbuf_lock writer-protection of ringbuffer printk: inline log_output(),log_store() in vprintk_store() printk: remove obsolete dead assignment printk/console: Allow to disable console output by using console="" or console=null init/console: Use ttynull as a fallback when there is no console printk: ringbuffer: Reference text_data_ring directly in callees.
2020-12-15Merge tag 'sched-core-2020-12-14' of ↵Linus Torvalds1-4/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Thomas Gleixner: - migrate_disable/enable() support which originates from the RT tree and is now a prerequisite for the new preemptible kmap_local() API which aims to replace kmap_atomic(). - A fair amount of topology and NUMA related improvements - Improvements for the frequency invariant calculations - Enhanced robustness for the global CPU priority tracking and decision making - The usual small fixes and enhancements all over the place * tag 'sched-core-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (61 commits) sched/fair: Trivial correction of the newidle_balance() comment sched/fair: Clear SMT siblings after determining the core is not idle sched: Fix kernel-doc markup x86: Print ratio freq_max/freq_base used in frequency invariance calculations x86, sched: Use midpoint of max_boost and max_P for frequency invariance on AMD EPYC x86, sched: Calculate frequency invariance for AMD systems irq_work: Optimize irq_work_single() smp: Cleanup smp_call_function*() irq_work: Cleanup sched: Limit the amount of NUMA imbalance that can exist at fork time sched/numa: Allow a floating imbalance between NUMA nodes sched: Avoid unnecessary calculation of load imbalance at clone time sched/numa: Rename nr_running and break out the magic number sched: Make migrate_disable/enable() independent of RT sched/topology: Condition EAS enablement on FIE support arm64: Rebuild sched domains on invariance status changes sched/topology,schedutil: Wrap sched domains rebuild sched/uclamp: Allow to reset a task uclamp constraint value sched/core: Fix typos in comments Documentation: scheduler: fix information on arch SD flags, sched_domain and sched_debug ...
2020-12-14Merge branch 'for-5.11' into for-linusPetr Mladek2-18/+15
2020-12-14Merge branch 'for-5.11-null-console' into for-linusPetr Mladek1-1/+8
2020-12-09printk: remove logbuf_lock writer-protection of ringbufferJohn Ogness1-40/+98
Since the ringbuffer is lockless, there is no need for it to be protected by @logbuf_lock. Remove @logbuf_lock writer-protection of the ringbuffer. The reader-protection is not removed because some variables, used by readers, are using @logbuf_lock for synchronization: @syslog_seq, @syslog_time, @syslog_partial, @console_seq, struct kmsg_dumper. For PRINTK_NMI_DIRECT_CONTEXT_MASK, @logbuf_lock usage is not removed because it may be used for dumper synchronization. Without @logbuf_lock synchronization of vprintk_store() it is no longer possible to use the single static buffer for temporarily sprint'ing the message. Instead, use vsnprintf() to determine the length and perform the real vscnprintf() using the area reserved from the ringbuffer. This leads to suboptimal packing of the message data, but will result in less wasted storage than multiple per-cpu buffers to support lockless temporary sprint'ing. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201209004453.17720-3-john.ogness@linutronix.de
2020-12-09printk: inline log_output(),log_store() in vprintk_store()John Ogness1-78/+67
In preparation for removing logbuf_lock, inline log_output() and log_store() into vprintk_store(). This will simplify dealing with the various code branches and fallbacks that are possible. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201209004453.17720-2-john.ogness@linutronix.de
2020-12-08printk: remove obsolete dead assignmentLukas Bulwahn1-1/+0
Commit 849f3127bb46 ("switch /dev/kmsg to ->write_iter()") refactored devkmsg_write() and left over a dead assignment on the variable 'len'. Hence, make clang-analyzer warns: kernel/printk/printk.c:744:4: warning: Value stored to 'len' is never read [clang-analyzer-deadcode.DeadStores] len -= endp - line; ^ Simply remove this obsolete dead assignment here. Link: https://lore.kernel.org/r/20201130124915.7573-1-lukas.bulwahn@gmail.com Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-11-27Merge tag 'printk-for-5.10-rc6-fixup' of ↵Linus Torvalds2-4/+2
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk fixes from Petr Mladek: - do not lose trailing newline in pr_cont() calls - two trivial fixes for a dead store and a config description * tag 'printk-for-5.10-rc6-fixup' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: finalize records with trailing newlines printk: remove unneeded dead-store assignment init/Kconfig: Fix CPU number in LOG_CPU_MAX_BUF_SHIFT description
2020-11-27Merge branch 'for-5.10-pr_cont-fixup' into for-linusPetr Mladek1-2/+2
2020-11-27printk: finalize records with trailing newlinesJohn Ogness1-2/+2
Any record with a trailing newline (LOG_NEWLINE flag) cannot be continued because the newline has been stripped and will not be visible if the message is appended. This was already handled correctly when committing in log_output() but was not handled correctly when committing in log_store(). Fixes: f5f022e53b87 ("printk: reimplement log_cont using record extension") Link: https://lore.kernel.org/r/20201126114836.14750-1-john.ogness@linutronix.de Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-11-27Merge branch 'linus' into sched/core, to resolve semantic conflictIngo Molnar1-1/+1
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-11-24irq_work: CleanupPeter Zijlstra1-4/+2
Get rid of the __call_single_node union and clean up the API a little to avoid external code relying on the structure layout as much. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
2020-11-20printk/console: Allow to disable console output by using console="" or ↵Petr Mladek1-1/+8
console=null The commit 48021f98130880dd74 ("printk: handle blank console arguments passed in.") prevented crash caused by empty console= parameter value. Unfortunately, this value is widely used on Chromebooks to disable the console output. The above commit caused performance regression because the messages were pushed on slow console even though nobody was watching it. Use ttynull driver explicitly for console="" and console=null parameters. It has been created for exactly this purpose. It causes that preferred_console is set. As a result, ttySX and ttyX are not used as a fallback. And only ttynull console gets registered by default. It still allows to register other consoles either by additional console= parameters or SPCR. It prevents regression because it worked this way even before. Also it is a sane semantic. Preventing output on all consoles should be done another way, for example, by introducing mute_console parameter. Link: https://lore.kernel.org/r/20201006025935.GA597@jagdpanzerIV.localdomain Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Guenter Roeck <linux@roeck-us.net> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201111135450.11214-3-pmladek@suse.com
2020-11-11printk: ringbuffer: Reference text_data_ring directly in callees.Nikolay Borisov1-17/+15
A bunch of functions in the new ringbuffer code take both a printk_ringbuffer struct and a separate prb_data_ring. This is a relic from an earlier version of the code when a second data ring was present. Since this is no longer the case remove the extra function argument from: - data_make_reusable() - data_push_tail() - data_alloc() - data_realloc() Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-11-06printk: remove unneeded dead-store assignmentLukas Bulwahn1-2/+0
make clang-analyzer on x86_64 defconfig caught my attention with: kernel/printk/printk_ringbuffer.c:885:3: warning: Value stored to 'desc' is never read [clang-analyzer-deadcode.DeadStores] desc = to_desc(desc_ring, head_id); ^ Commit b6cf8b3f3312 ("printk: add lockless ringbuffer") introduced desc_reserve() with this unneeded dead-store assignment. As discussed with John Ogness privately, this is probably just some minor left-over from previous iterations of the ringbuffer implementation. So, simply remove this unneeded dead assignment to make clang-analyzer happy. As compilers will detect this unneeded assignment and optimize this anyway, the resulting object code is identical before and after this change. No functional change. No change to object code. Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201106034005.18822-1-lukas.bulwahn@gmail.com
2020-10-31printk: ringbuffer: Replace zero-length array with flexible-array memberGustavo A. R. Silva1-1/+1
There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-10-16Merge tag 'printk-for-5.10-fixup' of ↵Linus Torvalds1-1/+4
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk fix from Petr Mladek: "Prevent overflow in the new lockless ringbuffer" * tag 'printk-for-5.10-fixup' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: ringbuffer: Wrong data pointer when appending small string
2020-10-16Merge branch 'for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial Pull trivial updates from Jiri Kosina: "The latest advances in computer science from the trivial queue" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: xtensa: fix Kconfig typo spelling.txt: Remove some duplicate entries mtd: rawnand: oxnas: cleanup/simplify code selftests: vm: add fragment CONFIG_GUP_BENCHMARK perf: Fix opt help text for --no-bpf-event HID: logitech-dj: Fix spelling in comment bootconfig: Fix kernel message mentioning CONFIG_BOOT_CONFIG MAINTAINERS: rectify MMP SUPPORT after moving cputype.h scif: Fix spelling of EACCES printk: fix global comment lib/bitmap.c: fix spello fs: Fix missing 'bit' in comment
2020-10-15printk: ringbuffer: Wrong data pointer when appending small stringPetr Mladek1-1/+4
data_realloc() returns wrong data pointer when the block is wrapped and the size is not increased. It might happen when pr_cont() wants to add only few characters and there is already a space for them because of alignment. It might cause writing outsite the buffer. It has been detected by LTP tests with KASAN enabled: [ 221.921944] oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=c,mems_allowed=0,oom_memcg=/0,task_memcg=in [ 221.922108] ================================================================== [ 221.922111] BUG: KASAN: global-out-of-bounds in vprintk_store+0x362/0x3d0 [ 221.922112] Write of size 2 at addr ffffffffba51dbcd by task memcg_test_1/11282 [ 221.922113] [ 221.922114] CPU: 1 PID: 11282 Comm: memcg_test_1 Not tainted 5.9.0-next-20201013 #1 [ 221.922116] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS 2.0b 07/27/2017 [ 221.922116] Call Trace: [ 221.922117] dump_stack+0xa4/0xd9 [ 221.922118] print_address_description.constprop.0+0x21/0x210 [ 221.922119] ? _raw_write_lock_bh+0xe0/0xe0 [ 221.922120] ? vprintk_store+0x362/0x3d0 [ 221.922121] kasan_report.cold+0x37/0x7c [ 221.922122] ? vprintk_store+0x362/0x3d0 [ 221.922123] check_memory_region+0x18c/0x1f0 [ 221.922124] memcpy+0x3c/0x60 [ 221.922125] vprintk_store+0x362/0x3d0 [ 221.922125] ? __ia32_sys_syslog+0x50/0x50 [ 221.922126] ? _raw_spin_lock_irqsave+0x9b/0x100 [ 221.922127] ? _raw_spin_lock_irq+0xf0/0xf0 [ 221.922128] ? __kasan_check_write+0x14/0x20 [ 221.922129] vprintk_emit+0x8d/0x1f0 [ 221.922130] vprintk_default+0x1d/0x20 [ 221.922131] vprintk_func+0x5a/0x100 [ 221.922132] printk+0xb2/0xe3 [ 221.922133] ? swsusp_write.cold+0x189/0x189 [ 221.922134] ? kernfs_vfs_xattr_set+0x60/0x60 [ 221.922134] ? _raw_write_lock_bh+0xe0/0xe0 [ 221.922135] ? trace_hardirqs_on+0x38/0x100 [ 221.922136] pr_cont_kernfs_path.cold+0x49/0x4b [ 221.922137] mem_cgroup_print_oom_context.cold+0x74/0xc3 [ 221.922138] dump_header+0x340/0x3bf [ 221.922139] oom_kill_process.cold+0xb/0x10 [ 221.922140] out_of_memory+0x1e9/0x860 [ 221.922141] ? oom_killer_disable+0x210/0x210 [ 221.922142] mem_cgroup_out_of_memory+0x198/0x1c0 [ 221.922143] ? mem_cgroup_count_precharge_pte_range+0x250/0x250 [ 221.922144] try_charge+0xa9b/0xc50 [ 221.922145] ? arch_stack_walk+0x9e/0xf0 [ 221.922146] ? memory_high_write+0x230/0x230 [ 221.922146] ? avc_has_extended_perms+0x830/0x830 [ 221.922147] ? stack_trace_save+0x94/0xc0 [ 221.922148] ? stack_trace_consume_entry+0x90/0x90 [ 221.922149] __memcg_kmem_charge+0x73/0x120 [ 221.922150] ? cred_has_capability+0x10f/0x200 [ 221.922151] ? mem_cgroup_can_attach+0x260/0x260 [ 221.922152] ? selinux_sb_eat_lsm_opts+0x2f0/0x2f0 [ 221.922153] ? obj_cgroup_charge+0x16b/0x220 [ 221.922154] ? kmem_cache_alloc+0x78/0x4c0 [ 221.922155] obj_cgroup_charge+0x122/0x220 [ 221.922156] ? vm_area_alloc+0x20/0x90 [ 221.922156] kmem_cache_alloc+0x78/0x4c0 [ 221.922157] vm_area_alloc+0x20/0x90 [ 221.922158] mmap_region+0x3ed/0x9a0 [ 221.922159] ? cap_mmap_addr+0x1d/0x80 [ 221.922160] do_mmap+0x3ee/0x720 [ 221.922161] vm_mmap_pgoff+0x16a/0x1c0 [ 221.922162] ? randomize_stack_top+0x90/0x90 [ 221.922163] ? copy_page_range+0x1980/0x1980 [ 221.922163] ksys_mmap_pgoff+0xab/0x350 [ 221.922164] ? find_mergeable_anon_vma+0x110/0x110 [ 221.922165] ? __audit_syscall_entry+0x1a6/0x1e0 [ 221.922166] __x64_sys_mmap+0x8d/0xb0 [ 221.922167] do_syscall_64+0x38/0x50 [ 221.922168] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 221.922169] RIP: 0033:0x7fe8f5e75103 [ 221.922172] Code: 54 41 89 d4 55 48 89 fd 53 4c 89 cb 48 85 ff 74 56 49 89 d9 45 89 f8 45 89 f2 44 89 e2 4c 89 ee 48 89 ef b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7d 5b 5d 41 5c 41 5d 41 5e 41 5f c3 66 2e 0f [ 221.922173] RSP: 002b:00007ffd38c90198 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 [ 221.922175] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe8f5e75103 [ 221.922176] RDX: 0000000000000003 RSI: 0000000000001000 RDI: 0000000000000000 [ 221.922178] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 221.922179] R10: 0000000000002022 R11: 0000000000000246 R12: 0000000000000003 [ 221.922180] R13: 0000000000001000 R14: 0000000000002022 R15: 0000000000000000 [ 221.922181] [ 213O[ 221.922182] The buggy address belongs to the variable: [ 221.922183] clear_seq+0x2d/0x40 [ 221.922183] [ 221.922184] Memory state around the buggy address: [ 221.922185] ffffffffba51da80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 221.922187] ffffffffba51db00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 221.922188] >ffffffffba51db80: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 [ 221.922189] ^ [ 221.922190] ffffffffba51dc00: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 [ 221.922191] ffffffffba51dc80: f9 f9 f9 f9 01 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 [ 221.922193] ================================================================== [ 221.922194] Disabling lock debugging due to kernel taint [ 221.922196] ,task=memcg_test_1,pid=11280,uid=0 [ 221.922205] Memory cgroup out of memory: Killed process 11280 Link: https://lore.kernel.org/r/CA+G9fYt46oC7-BKryNDaaXPJ9GztvS2cs_7GjYRjanRi4+ryCQ@mail.gmail.com Fixes: 4cfc7258f876a7feba673ac ("printk: ringbuffer: add finalization/extension support") Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Reviewed-by: John Ogness <john.ogness@linutronix.de> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201014175051.GC13775@alley
2020-10-12Merge branch 'printk-rework' into for-linusPetr Mladek6-577/+3042
2020-10-05printk: Use fallthrough pseudo-keywordGustavo A. R. Silva1-1/+1
Replace /* FALL THRU */ comment with the new pseudo-keyword macro fallthrough[1]. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201002224627.GA30475@embeddedor
2020-09-30printk: reduce setup_text_buf size to LOG_LINE_MAXJohn Ogness1-1/+1
@setup_text_buf only copies the original text messages (without any prefix or extended text). It only needs to be LOG_LINE_MAX in size. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200930090134.8723-3-john.ogness@linutronix.de
2020-09-30printk: avoid and/or handle record truncationJohn Ogness3-4/+19
If a reader provides a buffer that is smaller than the message text, the @text_len field of @info will have a value larger than the buffer size. If readers blindly read @text_len bytes of data without checking the size, they will read beyond their buffer. Add this check to record_print_text() to properly recognize when such truncation has occurred. Add a maximum size argument to the ringbuffer function to extend records so that records can not be created that are larger than the buffer size of readers. When extending records (LOG_CONT), do not extend records beyond LOG_LINE_MAX since that is the maximum size available in the buffers used by consoles and syslog. Fixes: f5f022e53b87 ("printk: reimplement log_cont using record extension") Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200930090134.8723-2-john.ogness@linutronix.de
2020-09-22printk: remove dict ringJohn Ogness3-200/+64
Since there is no code that will ever store anything into the dict ring, remove it. If any future dictionary properties are to be added, these should be added to the struct printk_info. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200918223421.21621-4-john.ogness@linutronix.de
2020-09-22printk: move dictionary keys to dev_printk_infoJohn Ogness4-83/+92
Dictionaries are only used for SUBSYSTEM and DEVICE properties. The current implementation stores the property names each time they are used. This requires more space than otherwise necessary. Also, because the dictionary entries are currently considered optional, it cannot be relied upon that they are always available, even if the writer wanted to store them. These issues will increase should new dictionary properties be introduced. Rather than storing the subsystem and device properties in the dict ring, introduce a struct dev_printk_info with separate fields to store only the property values. Embed this struct within the struct printk_info to provide guaranteed availability. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/87mu1jl6ne.fsf@jogness.linutronix.de
2020-09-22printk: move printk_info into separate arrayJohn Ogness3-71/+133
The majority of the size of a descriptor is taken up by meta data, which is often not of interest to the ringbuffer (for example, when performing state checks). Since descriptors are often temporarily stored on the stack, keeping their size minimal will help reduce stack pressure. Rather than embedding the printk_info into the descriptor, create a separate printk_info array. The index of a descriptor in the descriptor array corresponds to the printk_info with the same index in the printk_info array. The rules for validity of a printk_info match the existing rules for the data blocks: the descriptor must be in a consistent state. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200918223421.21621-2-john.ogness@linutronix.de
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