From: Zhihao Cheng <chengzhihao1@huawei.com> To: <miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>, <alexander.sverdlin@nokia.com>, <computersforpeace@gmail.com>, <maximlevitsky@gmail.com>, <David.Woodhouse@intel.com> Cc: <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>, <chengzhihao1@huawei.com>, <yukuai3@huawei.com> Subject: [PATCH v2] mtd: mtd_blkdevs: Get|Put mtd_device in add|del_mtd_blktrans Date: Tue, 15 Jun 2021 17:13:02 +0800 [thread overview] Message-ID: <20210615091302.3428611-1-chengzhihao1@huawei.com> (raw) There are two reasons to move mtd_device get|put operations into mtd blktrans adding/deleting: * Solve an AA-deadlock problem while formating mtd device to generate a ftl device. [<0>] blktrans_open+0x47/0x340 LOCK(mtd_table_mutex) [<0>] __blkdev_get+0x5b/0x3e0 [<0>] blkdev_get_by_dev+0x18f/0x370 [<0>] __device_add_disk+0x2db/0x700 [<0>] device_add_disk+0x17/0x20 [<0>] add_mtd_blktrans_dev+0x39e/0x6d0 [<0>] ftl_add_mtd+0x792/0x908 [ftl] [<0>] register_mtd_blktrans+0xfb/0x170 LOCK(mtd_table_mutex) [<0>] ftl_tr_init+0x18/0x1000 [ftl] [<0>] do_one_initcall+0x71/0x330 [<0>] do_init_module+0xa6/0x350 * Hold refcount of mtd device's module if mtd blktrans still exists. Module Size Used by mtdblock 20480 0 mtdram 20480 0 $ lsblk mtdblock0 31:0 0 64M 0 disk $ rmmod mtdram # mtd device is removed unexpectedly when mtdblock exists! $ lsmod Module Size Used by mtdblock 20480 0 $ lsblk // No mtdblock found ! Patched: Module Size Used by mtdblock 20480 0 mtdram 20480 1 $ lsblk mtdblock0 31:0 0 64M 0 disk $ rmmod mtdram # EBUSY, and /dev/mtdblock0 still exists , which works just like ubi/mtd: Module Size Used by ubi 380928 0 mtdram 20480 1 Fixes: 073db4a51ee43c ("mtd: fix: avoid race condition when ...") Fixes: 008c751ec78587 ("mtd: allow to unload the mtdtrans module if ...") Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> --- drivers/mtd/mtd_blkdevs.c | 25 ++++++------------------- 1 file changed, 6 insertions(+), 19 deletions(-) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index fb8e12d590a1..19a2870a097a 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -209,7 +209,6 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode) if (!dev) return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/ - mutex_lock(&mtd_table_mutex); mutex_lock(&dev->lock); if (dev->open) @@ -227,26 +226,18 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode) goto error_put; } - ret = __get_mtd_device(dev->mtd); - if (ret) - goto error_release; dev->file_mode = mode; unlock: dev->open++; mutex_unlock(&dev->lock); - mutex_unlock(&mtd_table_mutex); blktrans_dev_put(dev); return ret; -error_release: - if (dev->tr->release) - dev->tr->release(dev); error_put: module_put(dev->tr->owner); kref_put(&dev->ref, blktrans_dev_release); mutex_unlock(&dev->lock); - mutex_unlock(&mtd_table_mutex); blktrans_dev_put(dev); return ret; } @@ -258,7 +249,6 @@ static void blktrans_release(struct gendisk *disk, fmode_t mode) if (!dev) return; - mutex_lock(&mtd_table_mutex); mutex_lock(&dev->lock); if (--dev->open) @@ -267,14 +257,10 @@ static void blktrans_release(struct gendisk *disk, fmode_t mode) kref_put(&dev->ref, blktrans_dev_release); module_put(dev->tr->owner); - if (dev->mtd) { - if (dev->tr->release) - dev->tr->release(dev); - __put_mtd_device(dev->mtd); - } + if (dev->mtd && dev->tr->release) + dev->tr->release(dev); unlock: mutex_unlock(&dev->lock); - mutex_unlock(&mtd_table_mutex); blktrans_dev_put(dev); } @@ -425,6 +411,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) } gd->queue = new->rq; + __get_mtd_device(new->mtd); if (new->readonly) set_disk_ro(gd, 1); @@ -474,15 +461,15 @@ int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) blk_mq_unquiesce_queue(old->rq); blk_mq_unfreeze_queue(old->rq); - /* If the device is currently open, tell trans driver to close it, - then put mtd device, and don't touch it again */ + /* If the device is currently open, tell trans driver to close it */ mutex_lock(&old->lock); if (old->open) { if (old->tr->release) old->tr->release(old); - __put_mtd_device(old->mtd); } + __put_mtd_device(old->mtd); + /* At that point, we don't touch the mtd anymore */ old->mtd = NULL; mutex_unlock(&old->lock); -- 2.31.1
WARNING: multiple messages have this Message-ID (diff)
From: Zhihao Cheng <chengzhihao1@huawei.com> To: <miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>, <alexander.sverdlin@nokia.com>, <computersforpeace@gmail.com>, <maximlevitsky@gmail.com>, <David.Woodhouse@intel.com> Cc: <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>, <chengzhihao1@huawei.com>, <yukuai3@huawei.com> Subject: [PATCH v2] mtd: mtd_blkdevs: Get|Put mtd_device in add|del_mtd_blktrans Date: Tue, 15 Jun 2021 17:13:02 +0800 [thread overview] Message-ID: <20210615091302.3428611-1-chengzhihao1@huawei.com> (raw) There are two reasons to move mtd_device get|put operations into mtd blktrans adding/deleting: * Solve an AA-deadlock problem while formating mtd device to generate a ftl device. [<0>] blktrans_open+0x47/0x340 LOCK(mtd_table_mutex) [<0>] __blkdev_get+0x5b/0x3e0 [<0>] blkdev_get_by_dev+0x18f/0x370 [<0>] __device_add_disk+0x2db/0x700 [<0>] device_add_disk+0x17/0x20 [<0>] add_mtd_blktrans_dev+0x39e/0x6d0 [<0>] ftl_add_mtd+0x792/0x908 [ftl] [<0>] register_mtd_blktrans+0xfb/0x170 LOCK(mtd_table_mutex) [<0>] ftl_tr_init+0x18/0x1000 [ftl] [<0>] do_one_initcall+0x71/0x330 [<0>] do_init_module+0xa6/0x350 * Hold refcount of mtd device's module if mtd blktrans still exists. Module Size Used by mtdblock 20480 0 mtdram 20480 0 $ lsblk mtdblock0 31:0 0 64M 0 disk $ rmmod mtdram # mtd device is removed unexpectedly when mtdblock exists! $ lsmod Module Size Used by mtdblock 20480 0 $ lsblk // No mtdblock found ! Patched: Module Size Used by mtdblock 20480 0 mtdram 20480 1 $ lsblk mtdblock0 31:0 0 64M 0 disk $ rmmod mtdram # EBUSY, and /dev/mtdblock0 still exists , which works just like ubi/mtd: Module Size Used by ubi 380928 0 mtdram 20480 1 Fixes: 073db4a51ee43c ("mtd: fix: avoid race condition when ...") Fixes: 008c751ec78587 ("mtd: allow to unload the mtdtrans module if ...") Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> --- drivers/mtd/mtd_blkdevs.c | 25 ++++++------------------- 1 file changed, 6 insertions(+), 19 deletions(-) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index fb8e12d590a1..19a2870a097a 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -209,7 +209,6 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode) if (!dev) return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/ - mutex_lock(&mtd_table_mutex); mutex_lock(&dev->lock); if (dev->open) @@ -227,26 +226,18 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode) goto error_put; } - ret = __get_mtd_device(dev->mtd); - if (ret) - goto error_release; dev->file_mode = mode; unlock: dev->open++; mutex_unlock(&dev->lock); - mutex_unlock(&mtd_table_mutex); blktrans_dev_put(dev); return ret; -error_release: - if (dev->tr->release) - dev->tr->release(dev); error_put: module_put(dev->tr->owner); kref_put(&dev->ref, blktrans_dev_release); mutex_unlock(&dev->lock); - mutex_unlock(&mtd_table_mutex); blktrans_dev_put(dev); return ret; } @@ -258,7 +249,6 @@ static void blktrans_release(struct gendisk *disk, fmode_t mode) if (!dev) return; - mutex_lock(&mtd_table_mutex); mutex_lock(&dev->lock); if (--dev->open) @@ -267,14 +257,10 @@ static void blktrans_release(struct gendisk *disk, fmode_t mode) kref_put(&dev->ref, blktrans_dev_release); module_put(dev->tr->owner); - if (dev->mtd) { - if (dev->tr->release) - dev->tr->release(dev); - __put_mtd_device(dev->mtd); - } + if (dev->mtd && dev->tr->release) + dev->tr->release(dev); unlock: mutex_unlock(&dev->lock); - mutex_unlock(&mtd_table_mutex); blktrans_dev_put(dev); } @@ -425,6 +411,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) } gd->queue = new->rq; + __get_mtd_device(new->mtd); if (new->readonly) set_disk_ro(gd, 1); @@ -474,15 +461,15 @@ int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) blk_mq_unquiesce_queue(old->rq); blk_mq_unfreeze_queue(old->rq); - /* If the device is currently open, tell trans driver to close it, - then put mtd device, and don't touch it again */ + /* If the device is currently open, tell trans driver to close it */ mutex_lock(&old->lock); if (old->open) { if (old->tr->release) old->tr->release(old); - __put_mtd_device(old->mtd); } + __put_mtd_device(old->mtd); + /* At that point, we don't touch the mtd anymore */ old->mtd = NULL; mutex_unlock(&old->lock); -- 2.31.1 ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/
next reply other threads:[~2021-06-15 9:04 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-15 9:13 Zhihao Cheng [this message] 2021-06-15 9:13 ` [PATCH v2] mtd: mtd_blkdevs: Get|Put mtd_device in add|del_mtd_blktrans Zhihao Cheng 2021-06-15 9:27 ` Alexander Sverdlin 2021-06-15 9:27 ` Alexander Sverdlin 2021-07-12 13:36 ` Zhihao Cheng 2021-07-12 13:36 ` Zhihao Cheng
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