Commit d1bd8ead authored Dec 14, 2016 by Petr Mladek Committed by Linus Torvalds Dec 14, 2016

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>

parent 2d13bb64

include/linux/kdb.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -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 */

kernel/debug/kdb/kdb_io.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

kernel/debug/kdb/kdb_main.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -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

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