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console: rename acquire/release_console_sem() to console_lock/unlock()

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The -rt patches change the console_semaphore to console_mutex.  As a
result, a quite large chunk of the patches changes all
acquire/release_console_sem() to acquire/release_console_mutex()

This commit makes things use more neutral function names which dont make
implications about the underlying lock.

The only real change is the return value of console_trylock which is
inverted from try_acquire_console_sem()

This patch also paves the way to switching console_sem from a semaphore to
a mutex.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make console_trylock return 1 on success, per Geert]
Signed-off-by: Torben Hohn <torbenh@gmx.de>
Cc: Thomas Gleixner <tglx@tglx.de>
Cc: Greg KH <gregkh@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Torben Hohn
2011-01-25 15:07:35 -08:00
committed by Linus Torvalds
parent 3689456b4b
commit ac751efa6a
44 changed files with 336 additions and 328 deletions
Download Patch File Download Diff File Expand all files Collapse all files

100
kernel/printk.c
View File

@@ -97,7 +97,7 @@ static int console_locked, console_suspended;
/*
* logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
* It is also used in interesting ways to provide interlocking in
* release_console_sem().
* console_unlock();.
*/
static DEFINE_SPINLOCK(logbuf_lock);
@@ -501,7 +501,7 @@ static void _call_console_drivers(unsigned start,
/*
* Call the console drivers, asking them to write out
* log_buf[start] to log_buf[end - 1].
* The console_sem must be held.
* The console_lock must be held.
*/
static void call_console_drivers(unsigned start, unsigned end)
{
@@ -604,11 +604,11 @@ static int have_callable_console(void)
*
* This is printk(). It can be called from any context. We want it to work.
*
* We try to grab the console_sem. If we succeed, it's easy - we log the output and
* We try to grab the console_lock. If we succeed, it's easy - we log the output and
* call the console drivers. If we fail to get the semaphore we place the output
* into the log buffer and return. The current holder of the console_sem will
* notice the new output in release_console_sem() and will send it to the
* consoles before releasing the semaphore.
* notice the new output in console_unlock(); and will send it to the
* consoles before releasing the lock.
*
* One effect of this deferred printing is that code which calls printk() and
* then changes console_loglevel may break. This is because console_loglevel
@@ -659,19 +659,19 @@ static inline int can_use_console(unsigned int cpu)
/*
* Try to get console ownership to actually show the kernel
* messages from a 'printk'. Return true (and with the
* console_semaphore held, and 'console_locked' set) if it
* console_lock held, and 'console_locked' set) if it
* is successful, false otherwise.
*
* This gets called with the 'logbuf_lock' spinlock held and
* interrupts disabled. It should return with 'lockbuf_lock'
* released but interrupts still disabled.
*/
static int acquire_console_semaphore_for_printk(unsigned int cpu)
static int console_trylock_for_printk(unsigned int cpu)
__releases(&logbuf_lock)
{
int retval = 0;
if (!try_acquire_console_sem()) {
if (console_trylock()) {
retval = 1;
/*
@@ -827,12 +827,12 @@ asmlinkage int vprintk(const char *fmt, va_list args)
* actual magic (print out buffers, wake up klogd,
* etc).
*
* The acquire_console_semaphore_for_printk() function
* The console_trylock_for_printk() function
* will release 'logbuf_lock' regardless of whether it
* actually gets the semaphore or not.
*/
if (acquire_console_semaphore_for_printk(this_cpu))
release_console_sem();
if (console_trylock_for_printk(this_cpu))
console_unlock();
lockdep_on();
out_restore_irqs:
@@ -993,7 +993,7 @@ void suspend_console(void)
if (!console_suspend_enabled)
return;
printk("Suspending console(s) (use no_console_suspend to debug)\n");
acquire_console_sem();
console_lock();
console_suspended = 1;
up(&console_sem);
}
@@ -1004,7 +1004,7 @@ void resume_console(void)
return;
down(&console_sem);
console_suspended = 0;
release_console_sem();
console_unlock();
}
/**
@@ -1027,21 +1027,21 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
case CPU_DYING:
case CPU_DOWN_FAILED:
case CPU_UP_CANCELED:
acquire_console_sem();
release_console_sem();
console_lock();
console_unlock();
}
return NOTIFY_OK;
}
/**
* acquire_console_sem - lock the console system for exclusive use.
* console_lock - lock the console system for exclusive use.
*
* Acquires a semaphore which guarantees that the caller has
* Acquires a lock which guarantees that the caller has
* exclusive access to the console system and the console_drivers list.
*
* Can sleep, returns nothing.
*/
void acquire_console_sem(void)
void console_lock(void)
{
BUG_ON(in_interrupt());
down(&console_sem);
@@ -1050,21 +1050,29 @@ void acquire_console_sem(void)
console_locked = 1;
console_may_schedule = 1;
}
EXPORT_SYMBOL(acquire_console_sem);
EXPORT_SYMBOL(console_lock);
int try_acquire_console_sem(void)
/**
* console_trylock - try to lock the console system for exclusive use.
*
* Tried to acquire a lock which guarantees that the caller has
* exclusive access to the console system and the console_drivers list.
*
* returns 1 on success, and 0 on failure to acquire the lock.
*/
int console_trylock(void)
{
if (down_trylock(&console_sem))
return -1;
return 0;
if (console_suspended) {
up(&console_sem);
return -1;
return 0;
}
console_locked = 1;
console_may_schedule = 0;
return 0;
return 1;
}
EXPORT_SYMBOL(try_acquire_console_sem);
EXPORT_SYMBOL(console_trylock);
int is_console_locked(void)
{
@@ -1095,20 +1103,20 @@ void wake_up_klogd(void)
}
/**
* release_console_sem - unlock the console system
* console_unlock - unlock the console system
*
* Releases the semaphore which the caller holds on the console system
* Releases the console_lock which the caller holds on the console system
* and the console driver list.
*
* While the semaphore was held, console output may have been buffered
* by printk(). If this is the case, release_console_sem() emits
* the output prior to releasing the semaphore.
* While the console_lock was held, console output may have been buffered
* by printk(). If this is the case, console_unlock(); emits
* the output prior to releasing the lock.
*
* If there is output waiting for klogd, we wake it up.
*
* release_console_sem() may be called from any context.
* console_unlock(); may be called from any context.
*/
void release_console_sem(void)
void console_unlock(void)
{
unsigned long flags;
unsigned _con_start, _log_end;
@@ -1141,7 +1149,7 @@ void release_console_sem(void)
if (wake_klogd)
wake_up_klogd();
}
EXPORT_SYMBOL(release_console_sem);
EXPORT_SYMBOL(console_unlock);
/**
* console_conditional_schedule - yield the CPU if required
@@ -1150,7 +1158,7 @@ EXPORT_SYMBOL(release_console_sem);
* if this CPU should yield the CPU to another task, do
* so here.
*
* Must be called within acquire_console_sem().
* Must be called within console_lock();.
*/
void __sched console_conditional_schedule(void)
{
@@ -1171,14 +1179,14 @@ void console_unblank(void)
if (down_trylock(&console_sem) != 0)
return;
} else
acquire_console_sem();
console_lock();
console_locked = 1;
console_may_schedule = 0;
for_each_console(c)
if ((c->flags & CON_ENABLED) && c->unblank)
c->unblank();
release_console_sem();
console_unlock();
}
/*
@@ -1189,7 +1197,7 @@ struct tty_driver *console_device(int *index)
struct console *c;
struct tty_driver *driver = NULL;
acquire_console_sem();
console_lock();
for_each_console(c) {
if (!c->device)
continue;
@@ -1197,7 +1205,7 @@ struct tty_driver *console_device(int *index)
if (driver)
break;
}
release_console_sem();
console_unlock();
return driver;
}
@@ -1208,17 +1216,17 @@ struct tty_driver *console_device(int *index)
*/
void console_stop(struct console *console)
{
acquire_console_sem();
console_lock();
console->flags &= ~CON_ENABLED;
release_console_sem();
console_unlock();
}
EXPORT_SYMBOL(console_stop);
void console_start(struct console *console)
{
acquire_console_sem();
console_lock();
console->flags |= CON_ENABLED;
release_console_sem();
console_unlock();
}
EXPORT_SYMBOL(console_start);
@@ -1340,7 +1348,7 @@ void register_console(struct console *newcon)
* Put this console in the list - keep the
* preferred driver at the head of the list.
*/
acquire_console_sem();
console_lock();
if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
newcon->next = console_drivers;
console_drivers = newcon;
@@ -1352,14 +1360,14 @@ void register_console(struct console *newcon)
}
if (newcon->flags & CON_PRINTBUFFER) {
/*
* release_console_sem() will print out the buffered messages
* console_unlock(); will print out the buffered messages
* for us.
*/
spin_lock_irqsave(&logbuf_lock, flags);
con_start = log_start;
spin_unlock_irqrestore(&logbuf_lock, flags);
}
release_console_sem();
console_unlock();
console_sysfs_notify();
/*
@@ -1396,7 +1404,7 @@ int unregister_console(struct console *console)
return braille_unregister_console(console);
#endif
acquire_console_sem();
console_lock();
if (console_drivers == console) {
console_drivers=console->next;
res = 0;
@@ -1418,7 +1426,7 @@ int unregister_console(struct console *console)
if (console_drivers != NULL && console->flags & CON_CONSDEV)
console_drivers->flags |= CON_CONSDEV;
release_console_sem();
console_unlock();
console_sysfs_notify();
return res;
}