Hi Mark, On Mon, Aug 17, 2015 at 11:52 AM, Nicolas Boichat <drinkcat@xxxxxxxxxxxx> wrote: > chipselect (in the case of spi-gpio: spi_gpio_chipselect, which > calls gpiod_set_raw_value_cansleep) can sleep, so we should not > hold a spinlock while calling it from spi_bitbang_setup. > > This issue was introduced by this commit, which converted spi-gpio > to cansleep variants: > d9dda5a191 "spi: spi-gpio: Use 'cansleep' variants to access GPIO" > > Replacing the lock variable by a mutex fixes the issue: This is > safe as all instances where the lock is used are called from > contexts that can sleep. > > Finally, update spi-ppc4xx and and spi-s3c24xx to use mutex > functions, as they directly hold the lock for similar purpose. > > Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx> > --- > Going the "safer" way and just replacing the spinlock by a > mutex. > > Applies on top of broonie-sound/for-next, and compile-tested on > x86-64/arm (allyesconfig) and ppc44x (defconfig+SPI driver), > and runtime-tested on an arm platform. > > Thanks! Any update on this patch? It still applies on for-next but happy to resend if necessary (patchwork: https://patchwork.kernel.org/patch/7023091/). Best, > drivers/spi/spi-bitbang.c | 17 +++++++---------- > drivers/spi/spi-ppc4xx.c | 4 ++-- > drivers/spi/spi-s3c24xx.c | 4 ++-- > include/linux/spi/spi_bitbang.h | 2 +- > 4 files changed, 12 insertions(+), 15 deletions(-) > > diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c > index 840a498..ef43ef5 100644 > --- a/drivers/spi/spi-bitbang.c > +++ b/drivers/spi/spi-bitbang.c > @@ -180,7 +180,6 @@ int spi_bitbang_setup(struct spi_device *spi) > { > struct spi_bitbang_cs *cs = spi->controller_state; > struct spi_bitbang *bitbang; > - unsigned long flags; > > bitbang = spi_master_get_devdata(spi->master); > > @@ -210,12 +209,12 @@ int spi_bitbang_setup(struct spi_device *spi) > */ > > /* deselect chip (low or high) */ > - spin_lock_irqsave(&bitbang->lock, flags); > + mutex_lock(&bitbang->lock); > if (!bitbang->busy) { > bitbang->chipselect(spi, BITBANG_CS_INACTIVE); > ndelay(cs->nsecs); > } > - spin_unlock_irqrestore(&bitbang->lock, flags); > + mutex_unlock(&bitbang->lock); > > return 0; > } > @@ -255,13 +254,12 @@ static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t) > static int spi_bitbang_prepare_hardware(struct spi_master *spi) > { > struct spi_bitbang *bitbang; > - unsigned long flags; > > bitbang = spi_master_get_devdata(spi); > > - spin_lock_irqsave(&bitbang->lock, flags); > + mutex_lock(&bitbang->lock); > bitbang->busy = 1; > - spin_unlock_irqrestore(&bitbang->lock, flags); > + mutex_unlock(&bitbang->lock); > > return 0; > } > @@ -378,13 +376,12 @@ static int spi_bitbang_transfer_one(struct spi_master *master, > static int spi_bitbang_unprepare_hardware(struct spi_master *spi) > { > struct spi_bitbang *bitbang; > - unsigned long flags; > > bitbang = spi_master_get_devdata(spi); > > - spin_lock_irqsave(&bitbang->lock, flags); > + mutex_lock(&bitbang->lock); > bitbang->busy = 0; > - spin_unlock_irqrestore(&bitbang->lock, flags); > + mutex_unlock(&bitbang->lock); > > return 0; > } > @@ -427,7 +424,7 @@ int spi_bitbang_start(struct spi_bitbang *bitbang) > if (!master || !bitbang->chipselect) > return -EINVAL; > > - spin_lock_init(&bitbang->lock); > + mutex_init(&bitbang->lock); > > if (!master->mode_bits) > master->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags; > diff --git a/drivers/spi/spi-ppc4xx.c b/drivers/spi/spi-ppc4xx.c > index 54fb984..dd3d0a2 100644 > --- a/drivers/spi/spi-ppc4xx.c > +++ b/drivers/spi/spi-ppc4xx.c > @@ -210,12 +210,12 @@ static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t) > if (in_8(&hw->regs->cdm) != cdm) > out_8(&hw->regs->cdm, cdm); > > - spin_lock(&hw->bitbang.lock); > + mutex_lock(&hw->bitbang.lock); > if (!hw->bitbang.busy) { > hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE); > /* Need to ndelay here? */ > } > - spin_unlock(&hw->bitbang.lock); > + mutex_unlock(&hw->bitbang.lock); > > return 0; > } > diff --git a/drivers/spi/spi-s3c24xx.c b/drivers/spi/spi-s3c24xx.c > index f36bc32..4e7d1bf 100644 > --- a/drivers/spi/spi-s3c24xx.c > +++ b/drivers/spi/spi-s3c24xx.c > @@ -198,12 +198,12 @@ static int s3c24xx_spi_setup(struct spi_device *spi) > if (ret) > return ret; > > - spin_lock(&hw->bitbang.lock); > + mutex_lock(&hw->bitbang.lock); > if (!hw->bitbang.busy) { > hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE); > /* need to ndelay for 0.5 clocktick ? */ > } > - spin_unlock(&hw->bitbang.lock); > + mutex_unlock(&hw->bitbang.lock); > > return 0; > } > diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h > index 85578d4..154788e 100644 > --- a/include/linux/spi/spi_bitbang.h > +++ b/include/linux/spi/spi_bitbang.h > @@ -4,7 +4,7 @@ > #include <linux/workqueue.h> > > struct spi_bitbang { > - spinlock_t lock; > + struct mutex lock; > u8 busy; > u8 use_dma; > u8 flags; /* extra spi->mode support */ > -- > 2.5.0.276.gf5e568e > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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