[PATCH] spi: fix __spi_pump_messages deadlock

[PATCH] spi: fix __spi_pump_messages deadlock

[Thomas Perrot]

Signed-off-by: Thomas Perrot <thomas.perrot-cVvwS2TCF4I@public.gmane.org>
---
 drivers/spi/spi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0239b45..785080a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1192,7 +1192,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread,
 	}
 
 out:
-	if (!bus_locked)
+	if (bus_locked)
 		mutex_unlock(&master->bus_lock_mutex);
 
 	/* Prod the scheduler in case transfer_one() was busy waiting */
-- 
2.1.4

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Re: [PATCH] spi: fix __spi_pump_messages deadlock

[Mark Brown]

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On Fri, May 13, 2016 at 11:31:32AM +0200, Thomas Perrot wrote:
> Signed-off-by: Thomas Perrot <thomas.perrot-cVvwS2TCF4I@public.gmane.org>

This really isn't adequate, you need to provide a changelog.  Simply
saying that there is a deadlock is not enough, you need to say what the
deadlock is and why your change fixes it.

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[PATCH] spi: fix __spi_pump_messages deadlock

[Thomas Perrot]

The lock on the spi bus is never release at the end of call of the function
__spi_pump_messages.

Signed-off-by: Thomas Perrot <thomas.perrot-cVvwS2TCF4I@public.gmane.org>
---
 drivers/spi/spi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0239b45..785080a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1192,7 +1192,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread,
 	}
 
 out:
-	if (!bus_locked)
+	if (bus_locked)
 		mutex_unlock(&master->bus_lock_mutex);
 
 	/* Prod the scheduler in case transfer_one() was busy waiting */
-- 
2.1.4

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Re: [PATCH] spi: fix __spi_pump_messages deadlock

[Mark Brown]

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On Fri, May 13, 2016 at 02:58:32PM +0200, Thomas Perrot wrote:
> The lock on the spi bus is never release at the end of call of the function
> __spi_pump_messages.

So how does this deadlock, in what situations does this trigger?  If
there were a deadlock that happened every single time we tried to
transfer messages I'd expect people would have noticed...

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