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16 Apr 2024 14:46:41 -0700 From: Vishal Verma Date: Tue, 16 Apr 2024 15:46:17 -0600 Subject: [PATCH v2 2/4] dax/bus.c: fix locking for unregister_dax_dev / unregister_dax_mapping paths MIME-Version: 1.0 Message-Id: <20240416-vv-dax_abi_fixes-v2-2-d5f0c8ec162e@intel.com> References: <20240416-vv-dax_abi_fixes-v2-0-d5f0c8ec162e@intel.com> In-Reply-To: <20240416-vv-dax_abi_fixes-v2-0-d5f0c8ec162e@intel.com> To: Dan Williams , Dave Jiang , Alison Schofield , Andrew Morton Cc: linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, Vishal Verma X-Mailer: b4 0.14-dev-5ce50 X-Developer-Signature: v=1; a=openpgp-sha256; l=3520; i=vishal.l.verma@intel.com; h=from:subject:message-id; bh=6NKueYWbYilwLzm6MjvNGh3MReMQfTip+ZRQnpWHoXo=; b=owGbwMvMwCXGf25diOft7jLG02pJDGlyH/enyV98tmMC+0yHnLWTp0uWbraz8j0qZn/esdHYy npx0zWzjlIWBjEuBlkxRZa/ez4yHpPbns8TmOAIM4eVCWQIAxenAEzEbCMjQ8PDvw4XrybZf125 7XfaN/P1v1b6h32zlnnH4MHleGTHmVkM/7TzZp0N61T7+uvK3aknHi353rLU68rbOyWTCucncRQ uvskJAA== X-Developer-Key: i=vishal.l.verma@intel.com; a=openpgp; fpr=F8682BE134C67A12332A2ED07AFA61BEA3B84DFF X-Stat-Signature: ja9reui46y7kie3xcboesnakj6g31czf X-Rspamd-Queue-Id: 4DEAC14000F X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1713304021-33579 X-HE-Meta: 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 NFZ8AT5r Q8jngtuvXDc5M1XPv0ig3LoJypKfIRHzArPCeiuLdP4SP16YUwhpafvOr/0d1HdSUZFaYTzp1n6kaTKSZSTQVnocJSr04zwX+kaYn0vC3xeMUiwce0mzmjYMN8HQ7D2zjHasFEPJj3mUFe8nJ7esGxVOw/U1GkW4wC4MgnUgajOvoo0qVewLUbMmRr/cqBfbburdMgHPADFKqSzcigdHlSD+cZQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Commit c05ae9d85b47 ("dax/bus.c: replace driver-core lock usage by a local rwsem") was a bit overzealous in eliminating device_lock() usage, and ended up removing a couple of lock acquisitions which were needed, and as a result, fix some of the conditional locking missteps that the above commit introduced in unregister_dax_dev() and unregister_dax_mapping(). Fixes: c05ae9d85b47 ("dax/bus.c: replace driver-core lock usage by a local rwsem") Reported-by: Dan Williams Signed-off-by: Vishal Verma --- drivers/dax/bus.c | 44 ++++++++++---------------------------------- 1 file changed, 10 insertions(+), 34 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 7924dd542a13..4e04b228b080 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -465,26 +465,17 @@ static void free_dev_dax_ranges(struct dev_dax *dev_dax) trim_dev_dax_range(dev_dax); } -static void __unregister_dev_dax(void *dev) +static void unregister_dev_dax(void *dev) { struct dev_dax *dev_dax = to_dev_dax(dev); dev_dbg(dev, "%s\n", __func__); + down_write(&dax_region_rwsem); kill_dev_dax(dev_dax); device_del(dev); free_dev_dax_ranges(dev_dax); put_device(dev); -} - -static void unregister_dev_dax(void *dev) -{ - if (rwsem_is_locked(&dax_region_rwsem)) - return __unregister_dev_dax(dev); - - if (WARN_ON_ONCE(down_write_killable(&dax_region_rwsem) != 0)) - return; - __unregister_dev_dax(dev); up_write(&dax_region_rwsem); } @@ -560,15 +551,12 @@ static ssize_t delete_store(struct device *dev, struct device_attribute *attr, if (!victim) return -ENXIO; - rc = down_write_killable(&dax_region_rwsem); - if (rc) - return rc; - rc = down_write_killable(&dax_dev_rwsem); - if (rc) { - up_write(&dax_region_rwsem); - return rc; - } + device_lock(dev); + device_lock(victim); dev_dax = to_dev_dax(victim); + rc = down_write_killable(&dax_dev_rwsem); + if (rc) + return rc; if (victim->driver || dev_dax_size(dev_dax)) rc = -EBUSY; else { @@ -589,11 +577,12 @@ static ssize_t delete_store(struct device *dev, struct device_attribute *attr, rc = -EBUSY; } up_write(&dax_dev_rwsem); + device_unlock(victim); /* won the race to invalidate the device, clean it up */ if (do_del) devm_release_action(dev, unregister_dev_dax, victim); - up_write(&dax_region_rwsem); + device_unlock(dev); put_device(victim); return rc; @@ -705,7 +694,7 @@ static void dax_mapping_release(struct device *dev) put_device(parent); } -static void __unregister_dax_mapping(void *data) +static void unregister_dax_mapping(void *data) { struct device *dev = data; struct dax_mapping *mapping = to_dax_mapping(dev); @@ -713,25 +702,12 @@ static void __unregister_dax_mapping(void *data) dev_dbg(dev, "%s\n", __func__); - lockdep_assert_held_write(&dax_region_rwsem); - dev_dax->ranges[mapping->range_id].mapping = NULL; mapping->range_id = -1; device_unregister(dev); } -static void unregister_dax_mapping(void *data) -{ - if (rwsem_is_locked(&dax_region_rwsem)) - return __unregister_dax_mapping(data); - - if (WARN_ON_ONCE(down_write_killable(&dax_region_rwsem) != 0)) - return; - __unregister_dax_mapping(data); - up_write(&dax_region_rwsem); -} - static struct dev_dax_range *get_dax_range(struct device *dev) { struct dax_mapping *mapping = to_dax_mapping(dev);