| Message ID | 1848110.TJtF6nar8z@diego (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 03/18/2016 04:48 AM, Heiko Stübner wrote: > 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. I suggest bus_locked flag passed to __spi_pump_messages() by __spi_sync() be updated to take care of the fact that spi_bus_lock() may have acquired the mutex, so that below changes in __spi_pump_messages() are not needed. > > Fixes: 49023d2e4ead ("spi: core: Fix deadlock when sending messages") > Signed-off-by: Heiko Stuebner <heiko@sntech.de> > --- > 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 */ >
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 */
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@sntech.de> --- drivers/spi/spi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)