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platform/x86: ISST: Fix possible circular locking dependency detected

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As reported:

[  256.104522] ======================================================
[  256.113783] WARNING: possible circular locking dependency detected
[  256.120093] 5.16.0-rc6-yocto-standard+ #99 Not tainted
[  256.125362] ------------------------------------------------------
[  256.131673] intel-speed-sel/844 is trying to acquire lock:
[  256.137290] ffffffffc036f0d0 (punit_misc_dev_lock){+.+.}-{3:3}, at: isst_if_open+0x18/0x90 [isst_if_common]
[  256.147171]
[  256.147171] but task is already holding lock:
[  256.153135] ffffffff8ee7cb50 (misc_mtx){+.+.}-{3:3}, at: misc_open+0x2a/0x170
[  256.160407]
[  256.160407] which lock already depends on the new lock.
[  256.160407]
[  256.168712]
[  256.168712] the existing dependency chain (in reverse order) is:
[  256.176327]
[  256.176327] -> #1 (misc_mtx){+.+.}-{3:3}:
[  256.181946]        lock_acquire+0x1e6/0x330
[  256.186265]        __mutex_lock+0x9b/0x9b0
[  256.190497]        mutex_lock_nested+0x1b/0x20
[  256.195075]        misc_register+0x32/0x1a0
[  256.199390]        isst_if_cdev_register+0x65/0x180 [isst_if_common]
[  256.205878]        isst_if_probe+0x144/0x16e [isst_if_mmio]
...
[  256.241976]
[  256.241976] -> #0 (punit_misc_dev_lock){+.+.}-{3:3}:
[  256.248552]        validate_chain+0xbc6/0x1750
[  256.253131]        __lock_acquire+0x88c/0xc10
[  256.257618]        lock_acquire+0x1e6/0x330
[  256.261933]        __mutex_lock+0x9b/0x9b0
[  256.266165]        mutex_lock_nested+0x1b/0x20
[  256.270739]        isst_if_open+0x18/0x90 [isst_if_common]
[  256.276356]        misc_open+0x100/0x170
[  256.280409]        chrdev_open+0xa5/0x1e0
...

The call sequence suggested that misc_device /dev file can be opened
before misc device is yet to be registered, which is done only once.

Here punit_misc_dev_lock was used as common lock, to protect the
registration by multiple ISST HW drivers, one time setup, prevent
duplicate registry of misc device and prevent load/unload when device
is open.

We can split into locks:
- One which just prevent duplicate call to misc_register() and one
time setup. Also never call again if the misc_register() failed or
required one time setup is failed. This lock is not shared with
any misc device callbacks.

- The other lock protects registry, load and unload of HW drivers.

Sequence in isst_if_cdev_register()
- Register callbacks under punit_misc_dev_open_lock
- Call isst_misc_reg() which registers misc_device on the first
registry which is under punit_misc_dev_reg_lock, which is not
shared with callbacks.

Sequence in isst_if_cdev_unregister
Just opposite of isst_if_cdev_register

Reported-and-tested-by: Liwei Song <liwei.song@windriver.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20220112022521.54669-1-srinivas.pandruvada@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Srinivas Pandruvada 2022-01-11 18:25:21 -08:00 committed by Hans de Goede
parent a29012ab23
commit 17da2d5f93
1 changed files with 63 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

97
drivers/platform/x86/intel/speed_select_if/isst_if_common.c
View File

@ -596,7 +596,10 @@ static long isst_if_def_ioctl(struct file *file, unsigned int cmd,
return ret;
}
static DEFINE_MUTEX(punit_misc_dev_lock);
/* Lock to prevent module registration when already opened by user space */
static DEFINE_MUTEX(punit_misc_dev_open_lock);
/* Lock to allow one share misc device for all ISST interace */
static DEFINE_MUTEX(punit_misc_dev_reg_lock);
static int misc_usage_count;
static int misc_device_ret;
static int misc_device_open;
@ -606,7 +609,7 @@ static int isst_if_open(struct inode *inode, struct file *file)
int i, ret = 0;
/* Fail open, if a module is going away */
mutex_lock(&punit_misc_dev_lock);
mutex_lock(&punit_misc_dev_open_lock);
for (i = 0; i < ISST_IF_DEV_MAX; ++i) {
struct isst_if_cmd_cb *cb = &punit_callbacks[i];
@ -628,7 +631,7 @@ static int isst_if_open(struct inode *inode, struct file *file)
} else {
misc_device_open++;
}
mutex_unlock(&punit_misc_dev_lock);
mutex_unlock(&punit_misc_dev_open_lock);
return ret;
}
@ -637,7 +640,7 @@ static int isst_if_relase(struct inode *inode, struct file *f)
{
int i;
mutex_lock(&punit_misc_dev_lock);
mutex_lock(&punit_misc_dev_open_lock);
misc_device_open--;
for (i = 0; i < ISST_IF_DEV_MAX; ++i) {
struct isst_if_cmd_cb *cb = &punit_callbacks[i];
@ -645,7 +648,7 @@ static int isst_if_relase(struct inode *inode, struct file *f)
if (cb->registered)
module_put(cb->owner);
}
mutex_unlock(&punit_misc_dev_lock);
mutex_unlock(&punit_misc_dev_open_lock);
return 0;
}
@ -662,6 +665,43 @@ static struct miscdevice isst_if_char_driver = {
.fops = &isst_if_char_driver_ops,
};
static int isst_misc_reg(void)
{
mutex_lock(&punit_misc_dev_reg_lock);
if (misc_device_ret)
goto unlock_exit;
if (!misc_usage_count) {
misc_device_ret = isst_if_cpu_info_init();
if (misc_device_ret)
goto unlock_exit;
misc_device_ret = misc_register(&isst_if_char_driver);
if (misc_device_ret) {
isst_if_cpu_info_exit();
goto unlock_exit;
}
}
misc_usage_count++;
unlock_exit:
mutex_unlock(&punit_misc_dev_reg_lock);
return misc_device_ret;
}
static void isst_misc_unreg(void)
{
mutex_lock(&punit_misc_dev_reg_lock);
if (misc_usage_count)
misc_usage_count--;
if (!misc_usage_count && !misc_device_ret) {
misc_deregister(&isst_if_char_driver);
isst_if_cpu_info_exit();
}
mutex_unlock(&punit_misc_dev_reg_lock);
}
/**
* isst_if_cdev_register() - Register callback for IOCTL
* @device_type: The device type this callback handling.
@ -679,38 +719,31 @@ static struct miscdevice isst_if_char_driver = {
*/
int isst_if_cdev_register(int device_type, struct isst_if_cmd_cb *cb)
{
if (misc_device_ret)
return misc_device_ret;
int ret;
if (device_type >= ISST_IF_DEV_MAX)
return -EINVAL;
mutex_lock(&punit_misc_dev_lock);
mutex_lock(&punit_misc_dev_open_lock);
/* Device is already open, we don't want to add new callbacks */
if (misc_device_open) {
mutex_unlock(&punit_misc_dev_lock);
mutex_unlock(&punit_misc_dev_open_lock);
return -EAGAIN;
}
if (!misc_usage_count) {
int ret;
misc_device_ret = misc_register(&isst_if_char_driver);
if (misc_device_ret)
goto unlock_exit;
ret = isst_if_cpu_info_init();
if (ret) {
misc_deregister(&isst_if_char_driver);
misc_device_ret = ret;
goto unlock_exit;
}
}
memcpy(&punit_callbacks[device_type], cb, sizeof(*cb));
punit_callbacks[device_type].registered = 1;
misc_usage_count++;
unlock_exit:
mutex_unlock(&punit_misc_dev_lock);
mutex_unlock(&punit_misc_dev_open_lock);
return misc_device_ret;
ret = isst_misc_reg();
if (ret) {
/*
* No need of mutex as the misc device register failed
* as no one can open device yet. Hence no contention.
*/
punit_callbacks[device_type].registered = 0;
return ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(isst_if_cdev_register);
@ -725,16 +758,12 @@ EXPORT_SYMBOL_GPL(isst_if_cdev_register);
*/
void isst_if_cdev_unregister(int device_type)
{
mutex_lock(&punit_misc_dev_lock);
misc_usage_count--;
isst_misc_unreg();
mutex_lock(&punit_misc_dev_open_lock);
punit_callbacks[device_type].registered = 0;
if (device_type == ISST_IF_DEV_MBOX)
isst_delete_hash();
if (!misc_usage_count && !misc_device_ret) {
misc_deregister(&isst_if_char_driver);
isst_if_cpu_info_exit();
}
mutex_unlock(&punit_misc_dev_lock);
mutex_unlock(&punit_misc_dev_open_lock);
}
EXPORT_SYMBOL_GPL(isst_if_cdev_unregister);