Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752246AbbHQDxK (ORCPT ); Sun, 16 Aug 2015 23:53:10 -0400 Received: from mail-pd0-f173.google.com ([209.85.192.173]:35451 "EHLO mail-pd0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751852AbbHQDxI (ORCPT ); Sun, 16 Aug 2015 23:53:08 -0400 From: Nicolas Boichat To: Mark Brown Cc: Kukjin Kim , Krzysztof Kozlowski , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org Subject: [PATCH v2] spi: bitbang: Replace spinlock by mutex Date: Mon, 17 Aug 2015 11:52:54 +0800 Message-Id: <1439783574-5933-1-git-send-email-drinkcat@chromium.org> X-Mailer: git-send-email 2.5.0.276.gf5e568e Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4895 Lines: 159 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 --- 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! 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 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-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/