Subject: + printk-fix-lockdep-instrumentation-of-console_sem.patch added to -mm tree
To: jack@xxxxxxx,andriy.shevchenko@xxxxxxxxxxxxxxx,fabio.estevam@xxxxxxxxxxxxx,festevam@xxxxxxxxx,mingo@xxxxxxxxxx,peterz@xxxxxxxxxxxxx,rostedt@xxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 29 Apr 2014 14:55:24 -0700
The patch titled
Subject: printk: fix lockdep instrumentation of console_sem
has been added to the -mm tree. Its filename is
printk-fix-lockdep-instrumentation-of-console_sem.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/printk-fix-lockdep-instrumentation-of-console_sem.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/printk-fix-lockdep-instrumentation-of-console_sem.patch
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------------------------------------------------------
From: Jan Kara <jack@xxxxxxx>
Subject: 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: Jan Kara <jack@xxxxxxx>
Reported-by: Fabio Estevam <festevam@xxxxxxxxx>
Reported-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Tested-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk/printk.c | 46 +++++++++++++++++++++++++++------------
1 file changed, 32 insertions(+), 14 deletions(-)
diff -puN kernel/printk/printk.c~printk-fix-lockdep-instrumentation-of-console_sem kernel/printk/printk.c
--- a/kernel/printk/printk.c~printk-fix-lockdep-instrumentation-of-console_sem
+++ a/kernel/printk/printk.c
@@ -91,6 +91,29 @@ static struct lockdep_map console_lock_d
#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
* definitely not the perfect debug tool (we don't know if _WE_
@@ -1422,7 +1445,7 @@ static int console_trylock_for_printk(un
*/
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 @@ skip:
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 @@ skip:
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();
_
Patches currently in -mm which might be from jack@xxxxxxx are
fanotify-fan_mark_flush-avoid-having-to-provide-a-fake-invalid-fd-and-path.patch
fanotify-create-fan_access-event-for-readdir.patch
fs-notify-markc-trivial-cleanup.patch
fs-mpagec-forgotten-write_sync-in-case-of-data-integrity-write.patch
printk-split-code-for-making-free-space-in-the-log-buffer.patch
printk-ignore-too-long-messages.patch
printk-split-message-size-computation.patch
printk-shrink-too-long-messages.patch
printk-return-really-stored-message-length.patch
printk-remove-outdated-comment.patch
printk-release-lockbuf_lock-before-calling-console_trylock_for_printk.patch
printk-release-lockbuf_lock-before-calling-console_trylock_for_printk-fix.patch
printk-fix-lockdep-instrumentation-of-console_sem.patch
printk-enable-interrupts-before-calling-console_trylock_for_printk.patch
printk-remove-separate-printk_sched-buffers-and-use-printk-buf-instead.patch
fs-isofs-logging-clean-up.patch
linux-next.patch
mm-add-strictlimit-knob-v2.patch
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