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List:       linux-kernel
Subject:    [PATCH v3 04/12] PCI: Destroy pci dev only once
From:       Yinghai Lu <yinghai () kernel ! org>
Date:       2013-11-30 22:40:30
Message-ID: 1385851238-21085-5-git-send-email-yinghai () kernel ! org
[Download RAW message or body]

Mutliple removing via /sys will call pci_destroy_dev two times.

| When concurent removing pci devices which are in the same pci subtree
| via sysfs, such as:
| echo -n 1 > /sys/bus/pci/devices/0000\:10\:00.0/remove ; echo -n 1 >
| /sys/bus/pci/devices/0000\:1a\:01.0/remove
| (1a:01.0 device is downstream from the 10:00.0 bridge)
|
| the following warning will show:
| [ 1799.280918] ------------[ cut here ]------------
| [ 1799.336199] WARNING: CPU: 7 PID: 126 at lib/list_debug.c:53 __list_del_entry+0x63/0xd0()
| [ 1799.433093] list_del corruption, ffff8807b4a7c000->next is LIST_POISON1 (dead000000100100)
| [ 1800.276623] CPU: 7 PID: 126 Comm: kworker/u512:1 Tainted: G        W    3.12.0-rc5+ #196
| [ 1800.508918] Workqueue: sysfsd sysfs_schedule_callback_work
| [ 1800.574703]  0000000000000009 ffff8807adbadbd8 ffffffff8168b26c ffff8807c27d08a8
| [ 1800.663860]  ffff8807adbadc28 ffff8807adbadc18 ffffffff810711dc ffff8807adbadc68
| [ 1800.753130]  ffff8807b4a7c000 ffff8807b4a7c000 ffff8807ad089c00 0000000000000000
| [ 1800.842282] Call Trace:
| [ 1800.871651]  [<ffffffff8168b26c>] dump_stack+0x55/0x76
| [ 1800.933301]  [<ffffffff810711dc>] warn_slowpath_common+0x8c/0xc0
| [ 1801.005283]  [<ffffffff810712c6>] warn_slowpath_fmt+0x46/0x50
| [ 1801.074081]  [<ffffffff8135a343>] __list_del_entry+0x63/0xd0
| [ 1801.141839]  [<ffffffff8135a3c1>] list_del+0x11/0x40
| [ 1801.201320]  [<ffffffff813734da>] pci_remove_bus_device+0x6a/0xe0
| [ 1801.274279]  [<ffffffff8137356e>] pci_stop_and_remove_bus_device+0x1e/0x30
| [ 1801.356606]  [<ffffffff8137b20b>] remove_callback+0x2b/0x40
| [ 1801.423412]  [<ffffffff81251848>] sysfs_schedule_callback_work+0x18/0x60
| [ 1801.503744]  [<ffffffff8108eab5>] process_one_work+0x1f5/0x540
| [ 1801.573640]  [<ffffffff8108ea53>] ? process_one_work+0x193/0x540
| [ 1801.645616]  [<ffffffff8108f2ac>] worker_thread+0x11c/0x370
| [ 1801.712337]  [<ffffffff8108f190>] ? rescuer_thread+0x350/0x350
| [ 1801.782178]  [<ffffffff8109731d>] kthread+0xed/0x100
| [ 1801.841661]  [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160
| [ 1801.919919]  [<ffffffff8169cc3c>] ret_from_fork+0x7c/0xb0
| [ 1801.984608]  [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160
| [ 1802.062825] ---[ end trace d77f2054de000fb7 ]---
|
| This issue is related to the bug 54411:
| https://bugzilla.kernel.org/show_bug.cgi?id=54411

Add is_removed to record if pci_destroy_dev is called already.

During second calling, still have extra dev ref hold via
device_schedule_call, so we are safe to check dev->is_removed.

It fixes the problem In Gu's test.

-v2: add partial changelog from Gu Zheng <guz.fnst@cn.fujitsu.com>
     refresh after patch of moving device_del from Rafael.
-v3: use atomic operations to prevent racing that Rafael and Bjorn concern.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
 drivers/pci/probe.c  | 2 ++
 drivers/pci/remove.c | 8 +++++---
 include/linux/pci.h  | 1 +
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 12ec56c..edab71d 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1398,6 +1398,8 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
 	dev->match_driver = false;
 	ret = device_add(&dev->dev);
 	WARN_ON(ret < 0);
+
+	atomic_set(&dev->removed_count, -1);
 }
 
 struct pci_dev *__ref pci_scan_single_device(struct pci_bus *bus, int devfn)
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index f452148..122de10 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -20,9 +20,11 @@ static void pci_stop_dev(struct pci_dev *dev)
 
 static void pci_destroy_dev(struct pci_dev *dev)
 {
-	device_del(&dev->dev);
-
-	put_device(&dev->dev);
+	if (atomic_inc_and_test(&dev->removed_count)) {
+		device_del(&dev->dev);
+		put_device(&dev->dev);
+	} else
+		atomic_dec(&dev->removed_count);
 }
 
 void pci_remove_bus(struct pci_bus *bus)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 1084a15..1ca5438 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -316,6 +316,7 @@ struct pci_dev {
 	struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */
 
 	bool match_driver;		/* Skip attaching driver */
+	atomic_t	removed_count;	/* pci_destroy_dev is called */
 	/* These fields are used by common fixups */
 	unsigned int	transparent:1;	/* Subtractive decode PCI bridge */
 	unsigned int	multifunction:1;/* Part of multi-function device */
-- 
1.8.1.4

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