diff options
author | Mark Brown <broonie@kernel.org> | 2021-10-08 16:31:57 +0300 |
---|---|---|
committer | Mark Brown <broonie@kernel.org> | 2021-10-14 14:47:29 +0300 |
commit | 6098475d4cb48d821bdf453c61118c56e26294f0 (patch) | |
tree | ddd30f9c1cc1ffc9e4f9e1fcb3fe4abc53d2b121 /include | |
parent | 75b3cb97eb1f05042745c0655a7145b0262d4c5c (diff) |
spi: Fix deadlock when adding SPI controllers on SPI buses
Currently we have a global spi_add_lock which we take when adding new
devices so that we can check that we're not trying to reuse a chip
select that's already controlled. This means that if the SPI device is
itself a SPI controller and triggers the instantiation of further SPI
devices we trigger a deadlock as we try to register and instantiate
those devices while in the process of doing so for the parent controller
and hence already holding the global spi_add_lock. Since we only care
about concurrency within a single SPI bus move the lock to be per
controller, avoiding the deadlock.
This can be easily triggered in the case of spi-mux.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/spi/spi.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 8371bca13729..6b0b686f6f90 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -531,6 +531,9 @@ struct spi_controller { /* I/O mutex */ struct mutex io_mutex; + /* Used to avoid adding the same CS twice */ + struct mutex add_lock; + /* lock and mutex for SPI bus locking */ spinlock_t bus_lock_spinlock; struct mutex bus_lock_mutex; |