spi: don't lock the bus in __spi_pump_messages if it is already locked
From: Heiko Stuebner <heiko@...> Date: Fri, 18 Mar 2016 00:12:03 +0100
Commit-Message
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@...>
Patch-Comment
drivers/spi/spi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Statistics
- 2 lines added
- 2 lines removed
Changes
------------------------------ drivers/spi/spi.c -------------------------------
index de2f2f9..62f962b 100644
@@ -1160,7 +1160,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread,
}
}
+ 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 && !master->bus_lock_flag)
mutex_unlock(&master->bus_lock_mutex);
/* Prod the scheduler in case transfer_one() was busy waiting */