linux-kernel - [PATCH] ipmi: Clear drvdata when interface is removed by hotmod

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Message-Id: <1409821187-3864-1-git-send-email-indou.takao@jp.fujitsu.com>
Date:	Thu,  4 Sep 2014 17:59:47 +0900
From:	Takao Indoh <indou.takao@...fujitsu.com>
To:	Corey Minyard <minyard@....org>
Cc:	openipmi-developer@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, gouji.masayuki@...fujitsu.com
Subject: [PATCH] ipmi: Clear drvdata when interface is removed by hotmod

This patch fixes a bug on hotmod removing.

After ipmi interface is removed using hotmod, kernel panic occurs when
rmmod impi_si. For example, try this:

 # echo "remove,"`cat /proc/ipmi/0/params` > \
 /sys/module/ipmi_si/parameters/hotmod
 # rmmod ipmi_si

Then, rmmod fails with the following messages.

------------[ cut here ]------------
WARNING: CPU: 12 PID: 10819 at /mnt/repos/linux/lib/list_debug.c:53
__list_del_entry+0x63/0xd0()
(snip)
CPU: 12 PID: 10819 Comm: rmmod Not tainted 3.17.0-rc1 #19
Hardware name: FUJITSU-SV PRIMERGY BX920 S2/D3030, BIOS 080015
Rev.3D81.3030 02/10/2012
 0000000000000009 ffff88022d547d40 ffffffff81575778 ffff88022d547d88
 ffff88022d547d78 ffffffff8104ec5d ffff88023908cdb0 ffffffffa06fa4e0
 ffff8800bac20860 0000000000000000 0000000002046090 ffff88022d547dd8
Call Trace:
 [<ffffffff81575778>] dump_stack+0x45/0x56
 [<ffffffff8104ec5d>] warn_slowpath_common+0x7d/0xa0
 [<ffffffff8104eccc>] warn_slowpath_fmt+0x4c/0x50
 [<ffffffff811f60bf>] ? __kernfs_remove+0xdf/0x220
 [<ffffffff81291213>] __list_del_entry+0x63/0xd0
 [<ffffffff8129128d>] list_del+0xd/0x30
 [<ffffffffa06f285a>] cleanup_one_si+0x2a/0x230 [ipmi_si]
 [<ffffffffa06f2f05>] ipmi_pnp_remove+0x15/0x20 [ipmi_si]
 [<ffffffff8131c7d4>] pnp_device_remove+0x24/0x40
 [<ffffffff8137175f>] __device_release_driver+0x7f/0xf0
 [<ffffffff81372100>] driver_detach+0xb0/0xc0
 [<ffffffff81371415>] bus_remove_driver+0x55/0xd0
 [<ffffffff8137283c>] driver_unregister+0x2c/0x50
 [<ffffffff8131ca02>] pnp_unregister_driver+0x12/0x20
 [<ffffffffa06f347c>] cleanup_ipmi_si+0xbc/0xf0 [ipmi_si]
 [<ffffffff810c33f2>] SyS_delete_module+0x132/0x1c0
 [<ffffffff81002ab9>] ? do_notify_resume+0x59/0x80
 [<ffffffff8157c45a>] ? int_signal+0x12/0x17
 [<ffffffff8157c1d2>] system_call_fastpath+0x16/0x1b
---[ end trace 70b4377268f85c23 ]---

list_del in cleanup_one_si() fails because the smi_info is already
removed when hotmod removing.

When ipmi interface is removed by hotmod, smi_info is removed by
cleanup_one_si(), but it is still set in drvdata. Therefore when rmmod
ipmi_si, ipmi_pnp_remove tries to remove it again and fails.

By this patch, a pointer to smi_info in drvdata is cleared when hotmod
removing so that it will be not accessed when rmmod.

Signed-off-by: Takao Indoh <indou.takao@...fujitsu.com>
---
 drivers/char/ipmi/ipmi_si_intf.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 5d66568..20a3739 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -1904,8 +1904,14 @@ static int hotmod_handler(const char *val, struct kernel_param *kp)
 					continue;
 				if (e->si_type != si_type)
 					continue;
-				if (e->io.addr_data == addr)
-					cleanup_one_si(e);
+				if (e->io.addr_data != addr)
+					continue;
+
+				/* Clear driver data */
+				if (e->dev)
+					dev_set_drvdata(e->dev, NULL);
+
+				cleanup_one_si(e);
 			}
 			mutex_unlock(&smi_infos_lock);
 		}
@@ -2316,7 +2322,8 @@ static void ipmi_pnp_remove(struct pnp_dev *dev)
 {
 	struct smi_info *info = pnp_get_drvdata(dev);
 
-	cleanup_one_si(info);
+	if (info)
+		cleanup_one_si(info);
 }
 
 static const struct pnp_device_id pnp_dev_table[] = {
@@ -2621,7 +2628,8 @@ static int ipmi_pci_probe(struct pci_dev *pdev,
 static void ipmi_pci_remove(struct pci_dev *pdev)
 {
 	struct smi_info *info = pci_get_drvdata(pdev);
-	cleanup_one_si(info);
+	if (info)
+		cleanup_one_si(info);
 	pci_disable_device(pdev);
 }
 
@@ -2729,7 +2737,10 @@ static int ipmi_probe(struct platform_device *dev)
 static int ipmi_remove(struct platform_device *dev)
 {
 #ifdef CONFIG_OF
-	cleanup_one_si(dev_get_drvdata(&dev->dev));
+	struct smi_info *info = dev_get_drvdata(&dev->dev);
+
+	if (info)
+		cleanup_one_si(info);
 #endif
 	return 0;
 }
@@ -2796,7 +2807,11 @@ static int ipmi_parisc_probe(struct parisc_device *dev)
 
 static int ipmi_parisc_remove(struct parisc_device *dev)
 {
-	cleanup_one_si(dev_get_drvdata(&dev->dev));
+	struct smi_info *info = dev_get_drvdata(&dev->dev);
+
+	if (info)
+		cleanup_one_si(info);
+
 	return 0;
 }
 
-- 
1.8.3.1


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