From: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com
[ Upstream commit 17da2d5f93692086dd096a975225ffd5622d0bf8 ]
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.i... Reviewed-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../intel_speed_select_if/isst_if_common.c | 97 ++++++++++++------- 1 file changed, 63 insertions(+), 34 deletions(-)
diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_common.c b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c index 3de5a3c66529d..cf7b6dee82191 100644 --- a/drivers/platform/x86/intel_speed_select_if/isst_if_common.c +++ b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c @@ -529,7 +529,10 @@ 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; @@ -539,7 +542,7 @@ 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];
@@ -561,7 +564,7 @@ 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; } @@ -570,7 +573,7 @@ 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]; @@ -578,7 +581,7 @@ 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; } @@ -595,6 +598,43 @@ 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. @@ -612,38 +652,31 @@ 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);
@@ -658,16 +691,12 @@ 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);