Commit bd8d7cf5 authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds
Browse files

printk: fix lockdep instrumentation of console_sem



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: default avatarJan Kara <jack@suse.cz>
Reported-by: default avatarFabio Estevam <festevam@gmail.com>
Reported-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: default avatarFabio Estevam <fabio.estevam@freescale.com>
Tested-By: default avatarValdis Kletnieks <valdis.kletnieks@vt.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 608873ca
......@@ -90,6 +90,29 @@ static struct lockdep_map console_lock_dep_map = {
};
#endif
/*
* Helper macros to handle lockdep when locking/unlocking console_sem. We use
* macros instead of functions so that _RET_IP_ contains useful information.
*/
#define down_console_sem() do { \
down(&console_sem);\
mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
} while (0)
static int __down_trylock_console_sem(unsigned long ip)
{
if (down_trylock(&console_sem))
return 1;
mutex_acquire(&console_lock_dep_map, 0, 1, ip);
return 0;
}
#define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
#define up_console_sem() do { \
mutex_release(&console_lock_dep_map, 1, _RET_IP_);\
up(&console_sem);\
} while (0)
/*
* This is used for debugging the mess that is the VT code by
* keeping track if we have the console semaphore held. It's
......@@ -1422,7 +1445,7 @@ static int console_trylock_for_printk(unsigned int cpu)
*/
if (!can_use_console(cpu)) {
console_locked = 0;
up(&console_sem);
up_console_sem();
return 0;
}
return 1;
......@@ -1951,16 +1974,14 @@ void suspend_console(void)
printk("Suspending console(s) (use no_console_suspend to debug)\n");
console_lock();
console_suspended = 1;
up(&console_sem);
mutex_release(&console_lock_dep_map, 1, _RET_IP_);
up_console_sem();
}
void resume_console(void)
{
if (!console_suspend_enabled)
return;
down(&console_sem);
mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
down_console_sem();
console_suspended = 0;
console_unlock();
}
......@@ -2002,12 +2023,11 @@ void console_lock(void)
{
might_sleep();
down(&console_sem);
down_console_sem();
if (console_suspended)
return;
console_locked = 1;
console_may_schedule = 1;
mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
}
EXPORT_SYMBOL(console_lock);
......@@ -2021,15 +2041,14 @@ EXPORT_SYMBOL(console_lock);
*/
int console_trylock(void)
{
if (down_trylock(&console_sem))
if (down_trylock_console_sem())
return 0;
if (console_suspended) {
up(&console_sem);
up_console_sem();
return 0;
}
console_locked = 1;
console_may_schedule = 0;
mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
return 1;
}
EXPORT_SYMBOL(console_trylock);
......@@ -2091,7 +2110,7 @@ void console_unlock(void)
bool retry;
if (console_suspended) {
up(&console_sem);
up_console_sem();
return;
}
......@@ -2153,7 +2172,6 @@ void console_unlock(void)
local_irq_restore(flags);
}
console_locked = 0;
mutex_release(&console_lock_dep_map, 1, _RET_IP_);
/* Release the exclusive_console once it is used */
if (unlikely(exclusive_console))
......@@ -2161,7 +2179,7 @@ void console_unlock(void)
raw_spin_unlock(&logbuf_lock);
up(&console_sem);
up_console_sem();
/*
* Someone could have filled up the buffer again, so re-check if there's
......@@ -2206,7 +2224,7 @@ void console_unblank(void)
* oops_in_progress is set to 1..
*/
if (oops_in_progress) {
if (down_trylock(&console_sem) != 0)
if (down_trylock_console_sem() != 0)
return;
} else
console_lock();
......
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