On Fri, May 11, 2012 at 5:17 PM, Anton Vorontsov anton.vorontsov@linaro.org wrote:
This is a longstanding bug, almost unnoticeable when calling persistent_ram_write() for small buffers.
But when called for large data buffers, the write routine behaves incorrectly, as the size may never update: instead of clamping the size to the maximum buffer size, buffer_size_add_clamp() returns an error (which is never checked by the write routine, btw).
To fix this, we now use buffer_size_add() that actually clamps the size to the max value.
Also remove buffer_size_add_clamp(), it is no longer needed.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org
drivers/staging/android/persistent_ram.c | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-)
diff --git a/drivers/staging/android/persistent_ram.c b/drivers/staging/android/persistent_ram.c index 12444fd..13a12bc 100644 --- a/drivers/staging/android/persistent_ram.c +++ b/drivers/staging/android/persistent_ram.c @@ -79,23 +79,6 @@ static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a) } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); }
-/* increase the size counter, retuning an error if it hits the max size */ -static inline ssize_t buffer_size_add_clamp(struct persistent_ram_zone *prz,
- size_t a)
-{
- size_t old;
- size_t new;
- do {
- old = atomic_read(&prz->buffer->size);
- new = old + a;
- if (new > prz->buffer_size)
- return -ENOMEM;
- } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
- return 0;
-}
static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, uint8_t *data, size_t len, uint8_t *ecc) { @@ -300,7 +283,7 @@ int notrace persistent_ram_write(struct persistent_ram_zone *prz, c = prz->buffer_size; }
- buffer_size_add_clamp(prz, c);
- buffer_size_add(prz, c);
start = buffer_start_add(prz, c);
-- 1.7.9.2
Acked-by: Colin Cross ccross@android.com
This is a bug fix for a bug introduced in 3.4-rc1, it should go into 3.4 if there is another rc.