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SPI: use mutex not semaphore

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Make spi_write_then_read() use a mutex not a binary semaphore.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Brownell
2007-12-04 23:45:09 -08:00
committed by Linus Torvalds
parent f8fcc93319
commit 068f407086
1 changed files with 3 additions and 3 deletions
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6
drivers/spi/spi.c
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@@ -589,7 +589,7 @@ int spi_write_then_read(struct spi_device *spi,
const u8 *txbuf, unsigned n_tx, const u8 *txbuf, unsigned n_tx,
u8 *rxbuf, unsigned n_rx) u8 *rxbuf, unsigned n_rx)
{ {
static DECLARE_MUTEX(lock); static DEFINE_MUTEX(lock);
int status; int status;
struct spi_message message; struct spi_message message;
@@ -615,7 +615,7 @@ int spi_write_then_read(struct spi_device *spi,
} }
/* ... unless someone else is using the pre-allocated buffer */ /* ... unless someone else is using the pre-allocated buffer */
if (down_trylock(&lock)) { if (!mutex_trylock(&lock)) {
local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
if (!local_buf) if (!local_buf)
return -ENOMEM; return -ENOMEM;
@@ -634,7 +634,7 @@ int spi_write_then_read(struct spi_device *spi,
} }
if (x[0].tx_buf == buf) if (x[0].tx_buf == buf)
up(&lock); mutex_unlock(&lock);
else else
kfree(local_buf); kfree(local_buf);