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kdb: remove unused kdb_event handling 

kdb_event state variable is only set but never checked in the kernel
code.

http://www.spinics.net/lists/kdb/msg01733.html suggests that this
variable affected WARN_CONSOLE_UNLOCKED() in the original
implementation.  But this check never went upstream.

The semantic is unclear and racy.  The value is updated after the
kdb_printf_lock is acquired and after it is released.  It should be
symmetric at minimum.  The value should be manipulated either inside or
outside the locked area.

Fortunately, it seems that the original function is gone and we could
simply remove the state variable.

Link: http://lkml.kernel.org/r/1480412276-16690-2-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Petr Mladek 2016-12-14 15:05:52 -08:00 committed by Linus Torvalds
parent 2d13bb6494
commit d1bd8ead12
3 changed files with 0 additions and 4 deletions
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1
include/linux/kdb.h
View File

@ -77,7 +77,6 @@ extern int kdb_poll_idx;
* number whenever the kernel debugger is entered.
*/
extern int kdb_initial_cpu;
extern atomic_t kdb_event;
/* Types and messages used for dynamically added kdb shell commands */

2
kernel/debug/kdb/kdb_io.c
View File

@ -576,7 +576,6 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
KDB_STATE_SET(PRINTF_LOCK);
spin_lock_irqsave(&kdb_printf_lock, flags);
got_printf_lock = 1;
atomic_inc(&kdb_event);
} else {
__acquire(kdb_printf_lock);
}
@ -851,7 +850,6 @@ kdb_print_out:
got_printf_lock = 0;
spin_unlock_irqrestore(&kdb_printf_lock, flags);
KDB_STATE_CLEAR(PRINTF_LOCK);
atomic_dec(&kdb_event);
} else {
__release(kdb_printf_lock);
}

1
kernel/debug/kdb/kdb_main.c
View File

@ -60,7 +60,6 @@ int kdb_grep_trailing;
* Kernel debugger state flags
*/
int kdb_flags;
atomic_t kdb_event;
/*
* kdb_lock protects updates to kdb_initial_cpu. Used to