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author | Mika Westerberg <mika.westerberg@linux.intel.com> | 2019-03-19 16:48:41 +0200 |
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committer | Mika Westerberg <mika.westerberg@linux.intel.com> | 2019-04-18 11:18:51 +0300 |
commit | 09f11b6c99feaf86a26444bca85dc693b3f58f8b (patch) | |
tree | b2b89575c1cbe8351315a12d3cd085c6845acbab | |
parent | 4708384f35ff6e5aac3dd70555f8765ecf9b6d56 (diff) | |
download | linux-stable-09f11b6c99feaf86a26444bca85dc693b3f58f8b.tar.gz linux-stable-09f11b6c99feaf86a26444bca85dc693b3f58f8b.tar.bz2 linux-stable-09f11b6c99feaf86a26444bca85dc693b3f58f8b.zip |
thunderbolt: Take domain lock in switch sysfs attribute callbacks
switch_lock was introduced because it allowed serialization of device
authorization requests from userspace without need to take the big
domain lock (tb->lock). This was fine because device authorization with
ICM is just one command that is sent to the firmware. Now that we start
to handle all tunneling in the driver switch_lock is not enough because
we need to walk over the topology to establish paths.
For this reason drop switch_lock from the driver completely in favour of
big domain lock.
There is one complication, though. If userspace is waiting for the lock
in tb_switch_set_authorized(), it keeps the device_del() from removing
the sysfs attribute because it waits for active users to release the
attribute first which leads into following splat:
INFO: task kworker/u8:3:73 blocked for more than 61 seconds.
Tainted: G W 5.1.0-rc1+ #244
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u8:3 D12976 73 2 0x80000000
Workqueue: thunderbolt0 tb_handle_hotplug [thunderbolt]
Call Trace:
? __schedule+0x2e5/0x740
? _raw_spin_lock_irqsave+0x12/0x40
? prepare_to_wait_event+0xc5/0x160
schedule+0x2d/0x80
__kernfs_remove.part.17+0x183/0x1f0
? finish_wait+0x80/0x80
kernfs_remove_by_name_ns+0x4a/0x90
remove_files.isra.1+0x2b/0x60
sysfs_remove_group+0x38/0x80
sysfs_remove_groups+0x24/0x40
device_remove_attrs+0x3d/0x70
device_del+0x14c/0x360
device_unregister+0x15/0x50
tb_switch_remove+0x9e/0x1d0 [thunderbolt]
tb_handle_hotplug+0x119/0x5a0 [thunderbolt]
? process_one_work+0x1b7/0x420
process_one_work+0x1b7/0x420
worker_thread+0x37/0x380
? _raw_spin_unlock_irqrestore+0xf/0x30
? process_one_work+0x420/0x420
kthread+0x118/0x130
? kthread_create_on_node+0x60/0x60
ret_from_fork+0x35/0x40
We deal this by following what network stack did for some of their
attributes and use mutex_trylock() with restart_syscall(). This makes
userspace release the attribute allowing sysfs attribute removal to
progress before the write is restarted and eventually fail when the
attribute is removed.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
-rw-r--r-- | drivers/thunderbolt/switch.c | 45 | ||||
-rw-r--r-- | drivers/thunderbolt/tb.h | 3 |
2 files changed, 20 insertions, 28 deletions
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c index 5c2c0201ae7f..7fa4ab076404 100644 --- a/drivers/thunderbolt/switch.c +++ b/drivers/thunderbolt/switch.c @@ -10,15 +10,13 @@ #include <linux/idr.h> #include <linux/nvmem-provider.h> #include <linux/pm_runtime.h> +#include <linux/sched/signal.h> #include <linux/sizes.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include "tb.h" -/* Switch authorization from userspace is serialized by this lock */ -static DEFINE_MUTEX(switch_lock); - /* Switch NVM support */ #define NVM_DEVID 0x05 @@ -254,8 +252,8 @@ static int tb_switch_nvm_write(void *priv, unsigned int offset, void *val, struct tb_switch *sw = priv; int ret = 0; - if (mutex_lock_interruptible(&switch_lock)) - return -ERESTARTSYS; + if (!mutex_trylock(&sw->tb->lock)) + return restart_syscall(); /* * Since writing the NVM image might require some special steps, @@ -275,7 +273,7 @@ static int tb_switch_nvm_write(void *priv, unsigned int offset, void *val, memcpy(sw->nvm->buf + offset, val, bytes); unlock: - mutex_unlock(&switch_lock); + mutex_unlock(&sw->tb->lock); return ret; } @@ -364,10 +362,7 @@ static int tb_switch_nvm_add(struct tb_switch *sw) } nvm->non_active = nvm_dev; - mutex_lock(&switch_lock); sw->nvm = nvm; - mutex_unlock(&switch_lock); - return 0; err_nvm_active: @@ -384,10 +379,8 @@ static void tb_switch_nvm_remove(struct tb_switch *sw) { struct tb_switch_nvm *nvm; - mutex_lock(&switch_lock); nvm = sw->nvm; sw->nvm = NULL; - mutex_unlock(&switch_lock); if (!nvm) return; @@ -698,8 +691,8 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val) { int ret = -EINVAL; - if (mutex_lock_interruptible(&switch_lock)) - return -ERESTARTSYS; + if (!mutex_trylock(&sw->tb->lock)) + return restart_syscall(); if (sw->authorized) goto unlock; @@ -742,7 +735,7 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val) } unlock: - mutex_unlock(&switch_lock); + mutex_unlock(&sw->tb->lock); return ret; } @@ -799,15 +792,15 @@ static ssize_t key_show(struct device *dev, struct device_attribute *attr, struct tb_switch *sw = tb_to_switch(dev); ssize_t ret; - if (mutex_lock_interruptible(&switch_lock)) - return -ERESTARTSYS; + if (!mutex_trylock(&sw->tb->lock)) + return restart_syscall(); if (sw->key) ret = sprintf(buf, "%*phN\n", TB_SWITCH_KEY_SIZE, sw->key); else ret = sprintf(buf, "\n"); - mutex_unlock(&switch_lock); + mutex_unlock(&sw->tb->lock); return ret; } @@ -824,8 +817,8 @@ static ssize_t key_store(struct device *dev, struct device_attribute *attr, else if (hex2bin(key, buf, sizeof(key))) return -EINVAL; - if (mutex_lock_interruptible(&switch_lock)) - return -ERESTARTSYS; + if (!mutex_trylock(&sw->tb->lock)) + return restart_syscall(); if (sw->authorized) { ret = -EBUSY; @@ -840,7 +833,7 @@ static ssize_t key_store(struct device *dev, struct device_attribute *attr, } } - mutex_unlock(&switch_lock); + mutex_unlock(&sw->tb->lock); return ret; } static DEVICE_ATTR(key, 0600, key_show, key_store); @@ -886,8 +879,8 @@ static ssize_t nvm_authenticate_store(struct device *dev, bool val; int ret; - if (mutex_lock_interruptible(&switch_lock)) - return -ERESTARTSYS; + if (!mutex_trylock(&sw->tb->lock)) + return restart_syscall(); /* If NVMem devices are not yet added */ if (!sw->nvm) { @@ -935,7 +928,7 @@ static ssize_t nvm_authenticate_store(struct device *dev, } exit_unlock: - mutex_unlock(&switch_lock); + mutex_unlock(&sw->tb->lock); if (ret) return ret; @@ -949,8 +942,8 @@ static ssize_t nvm_version_show(struct device *dev, struct tb_switch *sw = tb_to_switch(dev); int ret; - if (mutex_lock_interruptible(&switch_lock)) - return -ERESTARTSYS; + if (!mutex_trylock(&sw->tb->lock)) + return restart_syscall(); if (sw->safe_mode) ret = -ENODATA; @@ -959,7 +952,7 @@ static ssize_t nvm_version_show(struct device *dev, else ret = sprintf(buf, "%x.%x\n", sw->nvm->major, sw->nvm->minor); - mutex_unlock(&switch_lock); + mutex_unlock(&sw->tb->lock); return ret; } diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h index 496dcd03ede1..f7b0c43c29a7 100644 --- a/drivers/thunderbolt/tb.h +++ b/drivers/thunderbolt/tb.h @@ -79,8 +79,7 @@ struct tb_switch_nvm { * @depth: Depth in the chain this switch is connected (ICM only) * * When the switch is being added or removed to the domain (other - * switches) you need to have domain lock held. For switch authorization - * internal switch_lock is enough. + * switches) you need to have domain lock held. */ struct tb_switch { struct device dev; |