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2014-06-04init/main.c: remove an ifdefAndrew Morton2-2/+4
Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04kthreads: kill CLONE_KERNEL, change kernel_thread(kernel_init) to avoid ↵Oleg Nesterov2-7/+1
CLONE_SIGHAND 1. Remove CLONE_KERNEL, it has no users and it is dangerous. The (old) comment says "List of flags we want to share for kernel threads" but this is not true, we do not want to share ->sighand by default. This flag can only be used if the caller is sure that both parent/child will never play with signals (say, allow_signal/etc). 2. Change rest_init() to clone kernel_init() without CLONE_SIGHAND. In this case CLONE_SIGHAND does not really hurt, and it looks like optimization because copy_sighand() can avoid kmem_cache_alloc(). But in fact this only adds the minor pessimization. kernel_init() is going to exec the init process, and de_thread() will need to unshare ->sighand and do kmem_cache_alloc(sighand_cachep) anyway, but it needs to do more work and take tasklist_lock and siglock. Signed-off-by: Oleg Nesterov <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Acked-by: Steven Rostedt <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Mathieu Desnoyers <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04init/main.c: add initcall_blacklist kernel parameterPrarit Bhargava2-0/+72
When a module is built into the kernel the module_init() function becomes an initcall. Sometimes debugging through dynamic debug can help, however, debugging built in kernel modules is typically done by changing the .config, recompiling, and booting the new kernel in an effort to determine exactly which module caused a problem. This patchset can be useful stand-alone or combined with initcall_debug. There are cases where some initcalls can hang the machine before the console can be flushed, which can make initcall_debug output inaccurate. Having the ability to skip initcalls can help further debugging of these scenarios. Usage: initcall_blacklist=<list of comma separated initcalls> ex) added "initcall_blacklist=sgi_uv_sysfs_init" as a kernel parameter and the log contains: blacklisting initcall sgi_uv_sysfs_init ... ... initcall sgi_uv_sysfs_init blacklisted ex) added "initcall_blacklist=foo_bar,sgi_uv_sysfs_init" as a kernel parameter and the log contains: blacklisting initcall foo_bar blacklisting initcall sgi_uv_sysfs_init ... ... initcall sgi_uv_sysfs_init blacklisted [[email protected]: tweak printk text] Signed-off-by: Prarit Bhargava <[email protected]> Cc: Richard Weinberger <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Josh Boyer <[email protected]> Cc: Rob Landley <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Frederic Weisbecker <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04init/main.c: don't use pr_debug()Andrew Morton1-2/+2
Pertially revert commit ea676e846a81 ("init/main.c: convert to pr_foo()"). Unbeknownst to me, pr_debug() is different from the other pr_foo() levels: pr_debug() is a no-op when DEBUG is not defined. Happily, init/main.c does have a #define DEBUG so we didn't break initcall_debug. But the functioning of initcall_debug should not be dependent upon the presence of that #define DEBUG. Reported-by: Russell King <[email protected]> Cc: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04fs/binfmt_flat.c: make old_reloc() staticAxel Lin1-1/+1
old_reloc() is only used in this file, make it static. Signed-off-by: Axel Lin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04fs/binfmt_elf.c: fix bool assignementsFabian Frederick1-2/+2
Fix coccinelle warnings. Signed-off-by: Fabian Frederick <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04fs/efs: convert printk(KERN_DEBUG to pr_debugFabian Frederick3-26/+17
All KERN_DEBUG callsites being under #ifdef DEBUG we can safely convert everything to pr_debug without changing current behaviour. Remove #ifdef DEBUG around pr_debugs only (suggested by Joe Perches) Signed-off-by: Fabian Frederick <[email protected]> Cc: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04fs/efs: add pr_fmt / use __func__Fabian Frederick6-35/+49
Also uniformize function arguments. Signed-off-by: Fabian Frederick <[email protected]> Cc: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04fs/efs: convert printk to pr_foo()Fabian Frederick5-35/+32
Convert all except KERN_DEBUG (pr_debug doesn't work the same as printk(KERN_DEBUG and requires special check) Signed-off-by: Fabian Frederick <[email protected]> Cc: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04scripts/checkpatch.pl: device_initcall is not the only __initcall substituteFabian Frederick1-2/+2
This patch adds a link to init.h to find appropriate initcall function to replace obsolete __initcall Signed-off-by: Fabian Frederick <[email protected]> Cc: Andy Whitcroft <[email protected]> Cc: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: check stable email addressJoe Perches1-0/+6
It should be [email protected], not [email protected]. Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: warn on unnecessary void function return statementsJoe Perches1-0/+7
void function lines that use a single tab then "return;" are generally unnecessary. Signed-off-by: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: prefer kstrto<foo> to sscanf(buf, "%<lhuidx>", &bar);Joe Perches1-0/+21
Use the kstrto<foo> functions in preference to sscanf. Signed-off-by: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: add warning for kmalloc/kzalloc with multiplyJoe Perches1-0/+24
Protect against sizeof overflows by preferring kmalloc_array/kcalloc over kmalloc/kzalloc with a sizeof multiply. Signed-off-by: Joe Perches <[email protected]> Cc: Andy Whitcroft <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: warn on #defines ending in semicolonJoe Perches1-0/+11
Using a #define ending in a semicolon is poor style and can lead to unexpected code paths being executed. Warn on uses of these #define types: #define foo[(...)] bar; #define foo[(...)] \ bar; Based on a patch from Borislav Petkov. Signed-off-by: Joe Perches <[email protected]> Cc: Borislav Petkov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: make --strict a default for files in drivers/net and net/Joe Perches1-0/+13
Networking files are generally more strictly conformant to linux-kernel style so make checkpatch more verbose by default for patches to files or when checking files in these directories. Signed-off-by: Joe Perches <[email protected]> Cc: Andy Whitcroft <[email protected]> Cc: David Miller <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: always warn on missing blank line after variable declaration blockJoe Perches1-10/+34
Make the test system wide, modify the message too. Signed-off-by: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04checkpatch: fix wildcard DT compatible string checkingRob Herring1-2/+4
We attempt to search for compatible strings which use a variable token in the documented name such as <chip> or <soc>. While this was attempted to be handled, it's utterly broken. The desired forms of matching are: vendor,<chip>-* vendor,name<part#>-* For <chip>, lower case characters and numbers are permitted. For <part#>, only numeric values are allowed. With this change, the number of missing compatible strings reported in arch/arm/boot/dts is reduced from 1071 to 960. Reported-by: Alexandre Belloni <[email protected]> Signed-off-by: Rob Herring <[email protected]> Tested-by: Geert Uytterhoeven <[email protected]> Cc: Florian Vaussard <[email protected]> Cc: Joe Perches <[email protected]> Cc: Andy Whitcroft <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04kernel/compat.c: use sizeof() instead of sizeofFabian Frederick1-4/+4
Fix 4 checkpatch warnings WARNING: sizeof *tv should be sizeof(*tv) Signed-off-by: Fabian Frederick <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Arnd Bergmann <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/asn1_decoder.c: kernel-doc warning fixFabian Frederick1-1/+1
Signed-off-by: Fabian Frederick <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/atomic64_test.c: convert printk(KERN_INFO to pr_infoFabian Frederick1-5/+8
Convert printk to current pr_foo() logging functions. Also add pr_fmt based on KBUILD_MODNAME to avoid repeating prefix. Prefix is now "atomic64_test: " Signed-off-by: Fabian Frederick <[email protected]> Cc: Luca Barbieri <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/bug.c: convert printk to pr_foo()Fabian Frederick1-11/+10
- Coalesce formats - "WARNING:" prefix unchanged to keep bug format. - printk(KERN_DEFAULT not converted. - define pr_fmt without prefix to avoid any default prefix update (suggested by Joe Perches). Signed-off-by: Fabian Frederick <[email protected]> Cc: Jeremy Fitzhardinge <[email protected]> Cc: Joe Perches <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/textsearch.c: move EXPORT_SYMBOL after functionsFabian Frederick1-5/+4
Fix checkpatch warning: "WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable" Signed-off-by: Fabian Frederick <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/nlattr.c: move EXPORT_SYMBOL after functionsFabian Frederick1-9/+8
Fix some checkpatch warnings: WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable Signed-off-by: Fabian Frederick <[email protected]> Cc: Pablo Neira <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/digsig.c: kernel-doc warning fixesFabian Frederick1-2/+3
Small typo and @return: -> Returns ... Signed-off-by: Fabian Frederick <[email protected]> Cc: Duan Jiong <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/crc32.c: remove unnecessary __constantFabian Frederick1-2/+2
Use cpu_to_le32 instead of __constant_cpu_to_le32. Signed-off-by: Fabian Frederick <[email protected]> Cc: "David S. Miller" <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/radix-tree.c: kernel-doc warning fixFabian Frederick1-1/+0
index has been removed from __radix_tree_delete_node in 449dd6984d0e47 ("mm: keep page cache radix tree nodes in check") Signed-off-by: Fabian Frederick <[email protected]> Cc: Johannes Weiner <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/plist.c: make CONFIG_DEBUG_PI_LIST selectableDan Streetman1-5/+10
Change CONFIG_DEBUG_PI_LIST to be user-selectable, and add a title and description. Remove the dependency on DEBUG_RT_MUTEXES since they were changed to use rbtrees, and there are other users of plists now. Signed-off-by: Dan Streetman <[email protected]> Acked-by: Steven Rostedt <[email protected]> Cc: Peter Zijlstra <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/btree.c: fix leak of whole btree nodesMinfei Huang1-0/+1
I use btree from 3.14-rc2 in my own module. When the btree module is removed, a warning arises: kmem_cache_destroy btree_node: Slab cache still has objects CPU: 13 PID: 9150 Comm: rmmod Tainted: GF O 3.14.0-rc2 #1 Hardware name: Inspur NF5270M3/NF5270M3, BIOS CHEETAH_2.1.3 09/10/2013 Call Trace: dump_stack+0x49/0x5d kmem_cache_destroy+0xcf/0xe0 btree_module_exit+0x10/0x12 [btree] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b The cause is that it doesn't release the last btree node, when height = 1 and fill = 1. [[email protected]: remove unneeded test of NULL] Signed-off-by: Minfei Huang <[email protected]> Cc: Joern Engel <[email protected]> Cc: Johannes Berg <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/vsprintf.c: fix comparison to boolFabian Frederick1-2/+2
Fixing 2 coccinelle warnings: lib/vsprintf.c:2350:2-9: WARNING: Assignment of bool to 0/1 lib/vsprintf.c:2389:3-10: WARNING: Assignment of bool to 0/1 Signed-off-by: Fabian Frederick <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/libcrc32c.c: use PTR_ERR_OR_ZEROFabian Frederick1-4/+1
replace IS_ERR/PTR_ERR Signed-off-by: Fabian Frederick <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/xz: enable all filters by default in KconfigLasse Collin1-12/+12
This restores the old behavior that existed before 2013-02-22, when changes were made by 64dbfb444c150 ("decompressors: drop dependency on CONFIG_EXPERT") and 5dc49c75a2 ("decompressors: make the default XZ_DEC_* config match the selected architecture"). Disabling the filters only makes sense on embedded systems. Signed-off-by: Lasse Collin <[email protected]> Acked-by: Kyle McMartin <[email protected]> Cc: Florian Fainelli <[email protected]> Cc: Phillip Lougher <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/plist.c: replace pr_debug with printk in plist_test()Dan Streetman1-2/+2
Replace pr_debug() in lib/plist.c test function plist_test() with printk(KERN_DEBUG ...). Without DEBUG defined, pr_debug() is complied out, but the entire plist_test() function is already inside CONFIG_DEBUG_PI_LIST, so printk should just be used directly. Signed-off-by: Dan Streetman <[email protected]> Reviewed-by: Steven Rostedt <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/xz: add comments for the intentionally missing break statementsLasse Collin1-0/+4
Signed-off-by: Lasse Collin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04lib/string.c: use the name "C-string" in commentsDan Carpenter1-4/+4
For strncpy() and friends the source string may or may not have an actual NUL character at the end. The documentation is confusing in this because it specifically mentions that you are passing a "NUL-terminated" string. Wikipedia says that "C-string" is an alternative name we can use instead. http://en.wikipedia.org/wiki/Null-terminated_string Signed-off-by: Dan Carpenter <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04kernel/printk: use symbolic defines for console loglevelsBorislav Petkov10-32/+36
... instead of naked numbers. Stuff in sysrq.c used to set it to 8 which is supposed to mean above default level so set it to DEBUG instead as we're terminating/killing all tasks and we want to be verbose there. Also, correct the check in x86_64_start_kernel which should be >= as we're clearly issuing the string there for all debug levels, not only the magical 10. Signed-off-by: Borislav Petkov <[email protected]> Acked-by: Kees Cook <[email protected]> Acked-by: Randy Dunlap <[email protected]> Cc: Joe Perches <[email protected]> Cc: Valdis Kletnieks <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: report dropping of messages from logbufWill Deacon1-2/+7
If the log ring buffer becomes full, we silently overwrite old messages with new data. console_unlock will detect this case and fast-forward the console_* pointers to skip over the corrupted data, but nothing will be reported to the user. This patch hijacks the first valid log message after detecting that we dropped messages and prefixes it with a note detailing how many messages were dropped. For long (~1000 char) messages, this will result in some truncation of the real message, but given that we're dropping things anyway, that doesn't seem to be the end of the world. Signed-off-by: Will Deacon <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Cc: Kay Sievers <[email protected]> Cc: Jan Kara <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04Documentation: expand/clarify debug documentationDan Streetman2-7/+21
The pr_debug() and related debug print macros all differ from the normal pr_XXX() macros, in that the normal ones print unconditionally, while the debug macros are compiled out unless DEBUG is defined or CONFIG_DYNAMIC_DEBUG is set. This isn't obvious, and the only way to find this out is either to review the actual printk.h code or to read CodingStyle, and the message there doesn't highlight the fact. Change Documentation/CodingStyle to clearly indicate that pr_debug() and related debug printing macros behave differently than all other pr_XXX() macros, and attempt to clarify when and where the different debug printing methods might be used. Add short comment to printk.h above the pr_XXX() macros indicating that while these macros print unconditionally, pr_debug() does not. Signed-off-by: Dan Streetman <[email protected]> Cc: Joe Perches <[email protected]> Cc: Fabian Frederick <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04timekeeping: use printk_deferred when holding timekeeping seqlockJohn Stultz2-9/+13
Jiri Bohac pointed out that there are rare but potential deadlock possibilities when calling printk while holding the timekeeping seqlock. This is due to printk() triggering console sem wakeup, which can cause scheduling code to trigger hrtimers which may try to read the time. Specifically, as Jiri pointed out, that path is: printk vprintk_emit console_unlock up(&console_sem) __up wake_up_process try_to_wake_up ttwu_do_activate ttwu_activate activate_task enqueue_task enqueue_task_fair hrtick_update hrtick_start_fair hrtick_start_fair get_time ktime_get --> endless loop on read_seqcount_retry(&timekeeper_seq, ...) This patch tries to avoid this issue by using printk_deferred (previously named printk_sched) which should defer printing via a irq_work_queue. Signed-off-by: John Stultz <[email protected]> Reported-by: Jiri Bohac <[email protected]> Reviewed-by: Steven Rostedt <[email protected]> Cc: Jan Kara <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Steven Rostedt <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: Add printk_deferred_onceJohn Stultz3-13/+13
Two of the three prink_deferred uses are really printk_once style uses, so add a printk_deferred_once macro to simplify those call sites. Signed-off-by: John Stultz <[email protected]> Reviewed-by: Steven Rostedt <[email protected]> Reviewed-by: Jan Kara <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Jiri Bohac <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: rename printk_sched to printk_deferredJohn Stultz5-7/+7
After learning we'll need some sort of deferred printk functionality in the timekeeping core, Peter suggested we rename the printk_sched function so it can be reused by needed subsystems. This only changes the function name. No logic changes. Signed-off-by: John Stultz <[email protected]> Reviewed-by: Steven Rostedt <[email protected]> Cc: Jan Kara <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Jiri Bohac <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: disable preemption for printk_schedJohn Stultz1-0/+2
An earlier change in -mm (printk: remove separate printk_sched buffers...), removed the printk_sched irqsave/restore lines since it was safe for current users. Since we may be expanding usage of printk_sched(), disable preepmtion for this function to make it more generally safe to call. Signed-off-by: John Stultz <[email protected]> Reviewed-by: Jan Kara <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Jiri Bohac <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Steven Rostedt <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: remove separate printk_sched buffers and use printk buf insteadSteven Rostedt1-18/+29
To prevent deadlocks with doing a printk inside the scheduler, printk_sched() was created. The issue is that printk has a console_sem that it can grab and release. The release does a wake up if there's a task pending on the sem, and this wake up grabs the rq locks that is held in the scheduler. This leads to a possible deadlock if the wake up uses the same rq as the one with the rq lock held already. What printk_sched() does is to save the printk write in a per cpu buffer and sets the PRINTK_PENDING_SCHED flag. On a timer tick, if this flag is set, the printk() is done against the buffer. There's a couple of issues with this approach. 1) If two printk_sched()s are called before the tick, the second one will overwrite the first one. 2) The temporary buffer is 512 bytes and is per cpu. This is a quite a bit of space wasted for something that is seldom used. In order to remove this, the printk_sched() can use the printk buffer instead, and delay the console_trylock()/console_unlock() to the queued work. Because printk_sched() would then be taking the logbuf_lock, the logbuf_lock must not be held while doing anything that may call into the scheduler functions, which includes wake ups. Unfortunately, printk() also has a console_sem that it uses, and on release, the up(&console_sem) may do a wake up of any pending waiters. This must be avoided while holding the logbuf_lock. Signed-off-by: Steven Rostedt <[email protected]> Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: enable interrupts before calling console_trylock_for_printk()Jan Kara1-11/+18
We need interrupts disabled when calling console_trylock_for_printk() only so that cpu id we pass to can_use_console() remains valid (for other things console_sem provides all the exclusion we need and deadlocks on console_sem due to interrupts are impossible because we use down_trylock()). However if we are rescheduled, we are guaranteed to run on an online cpu so we can easily just get the cpu id in can_use_console(). We can lose a bit of performance when we enable interrupts in vprintk_emit() and then disable them again in console_unlock() but OTOH it can somewhat reduce interrupt latency caused by console_unlock() especially since later in the patch series we will want to spin on console_sem in console_trylock_for_printk(). Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: fix lockdep instrumentation of console_semJan Kara1-14/+32
Printk calls mutex_acquire() / mutex_release() by hand to instrument lockdep about console_sem. However in some corner cases the instrumentation is missing. Fix the problem by creating helper functions for locking / unlocking console_sem which take care of lockdep instrumentation as well. Signed-off-by: Jan Kara <[email protected]> Reported-by: Fabio Estevam <[email protected]> Reported-by: Andy Shevchenko <[email protected]> Tested-by: Fabio Estevam <[email protected]> Tested-By: Valdis Kletnieks <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: release lockbuf_lock before calling console_trylock_for_printk()Jan Kara1-33/+21
There's no reason to hold lockbuf_lock when entering console_trylock_for_printk(). The first thing this function does is to call down_trylock(console_sem) and if that fails it immediately unlocks lockbuf_lock. So lockbuf_lock isn't needed for that branch. When down_trylock() succeeds, the rest of console_trylock() is OK without lockbuf_lock (it is called without it from other places), and the only remaining thing in console_trylock_for_printk() is can_use_console() call. For that call console_sem is enough (it iterates all consoles and checks CON_ANYTIME flag). So we drop logbuf_lock before entering console_trylock_for_printk() which simplifies the code. [[email protected]: fix have_callable_console() comment] Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: remove outdated commentJan Kara1-2/+1
Comment about interesting interlocking between lockbuf_lock and console_sem is outdated. It was added in 2002 by commit a880f45a48be during conversion of console_lock to console_sem + lockbuf_lock. At that time release_console_sem() (today's equivalent is console_unlock()) was indeed using lockbuf_lock to avoid races between trylock on console_sem in printk() and unlock of console_sem. However these days the interlocking is gone and the races are avoided by rechecking logbuf state after releasing console_sem. Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: return really stored message lengthPetr Mladek1-15/+21
I wonder if anyone uses printk return value but it is there and should be counted correctly. This patch modifies log_store() to return the number of really stored bytes from the 'text' part. Also it handles the return value in vprintk_emit(). Note that log_store() is used also in cont_flush() but we could ignore the return value there. The function works with characters that were already counted earlier. In addition, the store could newer fail here because the length of the printed text is limited by the "cont" buffer and "dict" is NULL. Signed-off-by: Petr Mladek <[email protected]> Cc: Jan Kara <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Kay Sievers <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: shrink too long messagesPetr Mladek1-3/+39
We might want to print at least part of too long messages and add some warning for debugging purpose. The question is how long the shrunken message should be. If we use the whole buffer, it might get rotated too soon. Let's try to use only 1/4 of the buffer for now. Also shrink the whole dictionary. We do not want to parse it or break it in the middle of some pair of values. It would not cause any real harm but still. Signed-off-by: Petr Mladek <[email protected]> Cc: Jan Kara <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Kay Sievers <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2014-06-04printk: split message size computationPetr Mladek1-3/+13
We will want to recompute the message size when shrinking too long messages. Let's put the code into separate function. The side effect of setting "pad_len" is not nice but it is worth removing the code duplication. Note that I will probably have one more usage for this function when handling messages safe way in NMI context. This patch does not change the existing behavior. Signed-off-by: Petr Mladek <[email protected]> Cc: Jan Kara <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Kay Sievers <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
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