7e1b1fc4da
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: fe480a2675 (Modules: only add drivers/ direcory if needed)
Cc: v2.6.21+ <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
95 lines
2 KiB
C
95 lines
2 KiB
C
/*
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* module.c - module sysfs fun for drivers
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*
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* This file is released under the GPLv2
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*
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*/
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include "base.h"
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static char *make_driver_name(struct device_driver *drv)
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{
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char *driver_name;
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driver_name = kasprintf(GFP_KERNEL, "%s:%s", drv->bus->name, drv->name);
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if (!driver_name)
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return NULL;
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return driver_name;
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}
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static void module_create_drivers_dir(struct module_kobject *mk)
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{
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static DEFINE_MUTEX(drivers_dir_mutex);
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mutex_lock(&drivers_dir_mutex);
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if (mk && !mk->drivers_dir)
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mk->drivers_dir = kobject_create_and_add("drivers", &mk->kobj);
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mutex_unlock(&drivers_dir_mutex);
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}
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void module_add_driver(struct module *mod, struct device_driver *drv)
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{
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char *driver_name;
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int no_warn;
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struct module_kobject *mk = NULL;
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if (!drv)
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return;
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if (mod)
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mk = &mod->mkobj;
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else if (drv->mod_name) {
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struct kobject *mkobj;
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/* Lookup built-in module entry in /sys/modules */
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mkobj = kset_find_obj(module_kset, drv->mod_name);
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if (mkobj) {
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mk = container_of(mkobj, struct module_kobject, kobj);
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/* remember our module structure */
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drv->p->mkobj = mk;
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/* kset_find_obj took a reference */
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kobject_put(mkobj);
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}
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}
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if (!mk)
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return;
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/* Don't check return codes; these calls are idempotent */
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no_warn = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
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driver_name = make_driver_name(drv);
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if (driver_name) {
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module_create_drivers_dir(mk);
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no_warn = sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
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driver_name);
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kfree(driver_name);
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}
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}
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void module_remove_driver(struct device_driver *drv)
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{
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struct module_kobject *mk = NULL;
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char *driver_name;
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if (!drv)
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return;
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sysfs_remove_link(&drv->p->kobj, "module");
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if (drv->owner)
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mk = &drv->owner->mkobj;
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else if (drv->p->mkobj)
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mk = drv->p->mkobj;
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if (mk && mk->drivers_dir) {
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driver_name = make_driver_name(drv);
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if (driver_name) {
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sysfs_remove_link(mk->drivers_dir, driver_name);
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kfree(driver_name);
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}
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}
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}
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