diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-12-18 14:34:27 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-12-18 14:34:27 -0800 |
| commit | e5233658201924fbcffa9a6886ebb08c4cee65f2 (patch) | |
| tree | c096aaede3e675245102199eea8bbec32f2fec0e /drivers/tty/tty_ldsem.c | |
| parent | 1aba038bbb2c7663cb80d785423694780a6dd72e (diff) | |
| parent | c2db11eca089b60148ded7467b956a547e8a2ae0 (diff) | |
Merge tag 'tty-3.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial fixes from Greg KH:
"Here are a few fixes for 3.13-rc5 that resolve a number of reported
tty and serial driver issues"
* tag 'tty-3.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
tty: xuartps: Properly guard sysrq specific code
n_tty: Fix apparent order of echoed output
serial: 8250_dw: add new ACPI IDs
serial: 8250_dw: Fix LCR workaround regression
tty: Fix hang at ldsem_down_read()
Diffstat (limited to 'drivers/tty/tty_ldsem.c')
| -rw-r--r-- | drivers/tty/tty_ldsem.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/tty/tty_ldsem.c b/drivers/tty/tty_ldsem.c index 22fad8ad5ac..d8a55e87877 100644 --- a/drivers/tty/tty_ldsem.c +++ b/drivers/tty/tty_ldsem.c @@ -86,11 +86,21 @@ static inline long ldsem_atomic_update(long delta, struct ld_semaphore *sem) return atomic_long_add_return(delta, (atomic_long_t *)&sem->count); } +/* + * ldsem_cmpxchg() updates @*old with the last-known sem->count value. + * Returns 1 if count was successfully changed; @*old will have @new value. + * Returns 0 if count was not changed; @*old will have most recent sem->count + */ static inline int ldsem_cmpxchg(long *old, long new, struct ld_semaphore *sem) { - long tmp = *old; - *old = atomic_long_cmpxchg(&sem->count, *old, new); - return *old == tmp; + long tmp = atomic_long_cmpxchg(&sem->count, *old, new); + if (tmp == *old) { + *old = new; + return 1; + } else { + *old = tmp; + return 0; + } } /* |