https://github.com/torvalds/linux
Revision 7e1b1fc4dabd6ec8e28baa0708866e13fa93c9b3 authored by Jiri Slaby on 10 June 2016, 08:54:32 UTC, committed by Greg Kroah-Hartman on 16 June 2016, 02:21:31 UTC
Modules which register drivers via standard path (driver_register) in parallel can cause a warning: WARNING: CPU: 2 PID: 3492 at ../fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80 sysfs: cannot create duplicate filename '/module/saa7146/drivers' Modules linked in: hexium_gemini(+) mxb(+) ... ... Call Trace: ... [<ffffffff812e63a2>] sysfs_warn_dup+0x62/0x80 [<ffffffff812e6487>] sysfs_create_dir_ns+0x77/0x90 [<ffffffff8140f2c4>] kobject_add_internal+0xb4/0x340 [<ffffffff8140f5b8>] kobject_add+0x68/0xb0 [<ffffffff8140f631>] kobject_create_and_add+0x31/0x70 [<ffffffff8157a703>] module_add_driver+0xc3/0xd0 [<ffffffff8155e5d4>] bus_add_driver+0x154/0x280 [<ffffffff815604c0>] driver_register+0x60/0xe0 [<ffffffff8145bed0>] __pci_register_driver+0x60/0x70 [<ffffffffa0273e14>] saa7146_register_extension+0x64/0x90 [saa7146] [<ffffffffa0033011>] hexium_init_module+0x11/0x1000 [hexium_gemini] ... As can be (mostly) seen, driver_register causes this call sequence: -> bus_add_driver -> module_add_driver -> module_create_drivers_dir The last one creates "drivers" directory in /sys/module/<...>. When this is done in parallel, the directory is attempted to be created twice at the same time. This can be easily reproduced by loading mxb and hexium_gemini in parallel: while :; do modprobe mxb & modprobe hexium_gemini wait rmmod mxb hexium_gemini saa7146_vv saa7146 done saa7146 calls pci_register_driver for both mxb and hexium_gemini, which means /sys/module/saa7146/drivers is to be created for both of them. Fix this by a new mutex in module_create_drivers_dir which makes the test-and-create "drivers" dir atomic. I inverted the condition and removed 'return' to avoid multiple unlocks or a goto. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Fixes: fe480a2675ed (Modules: only add drivers/ direcory if needed) Cc: v2.6.21+ <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 parent 75f0b68
Tip revision: 7e1b1fc4dabd6ec8e28baa0708866e13fa93c9b3 authored by Jiri Slaby on 10 June 2016, 08:54:32 UTC
base: make module_create_drivers_dir race-free
base: make module_create_drivers_dir race-free
Tip revision: 7e1b1fc
File | Mode | Size |
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Documentation | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.get_maintainer.ignore | -rw-r--r-- | 31 bytes |
.gitignore | -rw-r--r-- | 1.2 KB |
.mailmap | -rw-r--r-- | 5.8 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 95.5 KB |
Kbuild | -rw-r--r-- | 2.8 KB |
Kconfig | -rw-r--r-- | 252 bytes |
MAINTAINERS | -rw-r--r-- | 352.7 KB |
Makefile | -rw-r--r-- | 56.0 KB |
README | -rw-r--r-- | 18.1 KB |
REPORTING-BUGS | -rw-r--r-- | 7.3 KB |
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