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From:   Todd Poynor <toddpoynor@gmail.com>
To:     Rob Springer <rspringer@google.com>,
        John Joseph <jnjoseph@google.com>,
        Ben Chan <benchan@chromium.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Zhongze Hu <frankhu@chromium.org>, Simon Que <sque@chromium.org>,
        Dmitry Torokhov <dtor@chromium.org>,
        Guenter Roeck <groeck@chromium.org>,
        devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org,
        Todd Poynor <toddpoynor@google.com>
Subject: [PATCH 06/18] staging: gasket: fix deadlock in pci driver unregister path
Date:   Fri, 13 Jul 2018 22:58:04 -0700
Message-Id: <20180714055816.223754-7-toddpoynor@gmail.com>
In-Reply-To: <20180714055816.223754-1-toddpoynor@gmail.com>
References: <20180714055816.223754-1-toddpoynor@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Todd Poynor <toddpoynor@google.com>

g_mutex held across pci_unregister_driver() call, also held in
gasket_pci_remove(), which deadlocks.

Reported-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Zhongze Hu <frankhu@chromium.org>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
---
 drivers/staging/gasket/gasket_core.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/gasket/gasket_core.c b/drivers/staging/gasket/gasket_core.c
index 3bdf7d36b397..6d240dc59557 100644
--- a/drivers/staging/gasket/gasket_core.c
+++ b/drivers/staging/gasket/gasket_core.c
@@ -668,13 +668,10 @@ static void gasket_pci_remove(struct pci_dev *pci_dev)
 	struct gasket_dev *gasket_dev = NULL;
 	const struct gasket_driver_desc *driver_desc;
 	/* Find the device desc. */
-	mutex_lock(&g_mutex);
+	__must_hold(&g_mutex);
 	internal_desc = lookup_internal_desc(pci_dev);
-	if (!internal_desc) {
-		mutex_unlock(&g_mutex);
+	if (!internal_desc)
 		return;
-	}
-	mutex_unlock(&g_mutex);
 
 	driver_desc = internal_desc->driver_desc;
 
-- 
2.18.0.203.gfac676dfb9-goog