[PATCH] spi: don't lock the bus in __spi_pump_messages if it is already locked

["Heiko Stübner" <heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org>]

External users may use spi_bus_lock to get exclusive access. This will
also grab the bus_lock_mutex and may therefore result in a deadlock if
__spi_pump_messages also tries to get the mutex.

Fixes: 49023d2e4ead ("spi: core: Fix deadlock when sending messages")
Signed-off-by: Heiko Stuebner <heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org>
---
 drivers/spi/spi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index de2f2f9..62f962b 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1160,7 +1160,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread,
 		}
 	}
 
-	if (!bus_locked)
+	if (!bus_locked && !master->bus_lock_flag)
 		mutex_lock(&master->bus_lock_mutex);
 
 	trace_spi_message_start(master->cur_msg);
@@ -1192,7 +1192,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread,
 	}
 
 out:
-	if (!bus_locked)
+	if (!bus_locked && !master->bus_lock_flag)
 		mutex_unlock(&master->bus_lock_mutex);
 
 	/* Prod the scheduler in case transfer_one() was busy waiting */
-- 
2.6.4


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