From: Xiubo Li <[email protected]>
The V2 patch set maybe not post successfully, so post it again
with one new updation.
V2:
- resend it with some small fix
V3:
- switch to use request_threaded_irq
Xiubo Li (3):
uio: use request_threaded_irq instead
uio: change to use the mutex lock instead of the spin lock
uio: fix crash after the device is unregistered
drivers/uio/uio.c | 151 ++++++++++++++++++++++++++++++++++-----------
include/linux/uio_driver.h | 2 +-
2 files changed, 115 insertions(+), 38 deletions(-)
--
1.8.3.1
From: Xiubo Li <[email protected]>
Prepraing for changing to use mutex lock.
Signed-off-by: Xiubo Li <[email protected]>
---
drivers/uio/uio.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index e8f4ac9..b4b2ae1 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -902,8 +902,9 @@ int __uio_register_device(struct module *owner,
* FDs at the time of unregister and therefore may not be
* freed until they are released.
*/
- ret = request_irq(info->irq, uio_interrupt,
- info->irq_flags, info->name, idev);
+ ret = request_threaded_irq(info->irq, NULL, uio_interrupt,
+ info->irq_flags, info->name, idev);
+
if (ret)
goto err_request_irq;
}
--
1.8.3.1
From: Xiubo Li <[email protected]>
For the target_core_user use case, after the device is unregistered
it maybe still opened in user space, then the kernel will crash, like:
[ 251.163692] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 251.163820] IP: [<ffffffffc0736213>] show_name+0x23/0x40 [uio]
[ 251.163965] PGD 8000000062694067 PUD 62696067 PMD 0
[ 251.164097] Oops: 0000 [#1] SMP
...
[ 251.165605] e1000 mptscsih mptbase drm_panel_orientation_quirks dm_mirror dm_region_hash dm_log dm_mod
[ 251.166014] CPU: 0 PID: 13380 Comm: tcmu-runner Kdump: loaded Not tainted 3.10.0-916.el7.test.x86_64 #1
[ 251.166381] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
[ 251.166747] task: ffff971eb91db0c0 ti: ffff971e9e384000 task.ti: ffff971e9e384000
[ 251.167137] RIP: 0010:[<ffffffffc0736213>] [<ffffffffc0736213>] show_name+0x23/0x40 [uio]
[ 251.167563] RSP: 0018:ffff971e9e387dc8 EFLAGS: 00010282
[ 251.167978] RAX: 0000000000000000 RBX: ffff971e9e3f8000 RCX: ffff971eb8368d98
[ 251.168408] RDX: ffff971e9e3f8000 RSI: ffffffffc0738084 RDI: ffff971e9e3f8000
[ 251.168856] RBP: ffff971e9e387dd0 R08: ffff971eb8bc0018 R09: 0000000000000000
[ 251.169296] R10: 0000000000001000 R11: ffffffffa09d444d R12: ffffffffa1076e80
[ 251.169750] R13: ffff971e9e387f18 R14: 0000000000000001 R15: ffff971e9cfb1c80
[ 251.170213] FS: 00007ff37d175880(0000) GS:ffff971ebb600000(0000) knlGS:0000000000000000
[ 251.170693] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 251.171248] CR2: 0000000000000008 CR3: 00000000001f6000 CR4: 00000000003607f0
[ 251.172071] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 251.172640] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 251.173236] Call Trace:
[ 251.173789] [<ffffffffa0c9b2d3>] dev_attr_show+0x23/0x60
[ 251.174356] [<ffffffffa0f561b2>] ? mutex_lock+0x12/0x2f
[ 251.174892] [<ffffffffa0ac6d9f>] sysfs_kf_seq_show+0xcf/0x1f0
[ 251.175433] [<ffffffffa0ac54e6>] kernfs_seq_show+0x26/0x30
[ 251.175981] [<ffffffffa0a63be0>] seq_read+0x110/0x3f0
[ 251.176609] [<ffffffffa0ac5d45>] kernfs_fop_read+0xf5/0x160
[ 251.177158] [<ffffffffa0a3d3af>] vfs_read+0x9f/0x170
[ 251.177707] [<ffffffffa0a3e27f>] SyS_read+0x7f/0xf0
[ 251.178268] [<ffffffffa0f648af>] system_call_fastpath+0x1c/0x21
[ 251.178823] Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 53 48 89 d3 e8 7e 96 56 e0 48 8b 80 d8 02 00 00 48 89 df 48 c7 c6 84 80 73 c0 <48> 8b 50 08 31 c0 e8 e2 67 44 e0 5b 48 98 5d c3 0f 1f 00 66 2e
[ 251.180115] RIP [<ffffffffc0736213>] show_name+0x23/0x40 [uio]
[ 251.180820] RSP <ffff971e9e387dc8>
[ 251.181473] CR2: 0000000000000008
CC: Hamish Martin <[email protected]>
CC: Mike Christie <[email protected]>
Signed-off-by: Xiubo Li <[email protected]>
---
drivers/uio/uio.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 99 insertions(+), 17 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 655ade4..a0d926e 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -215,7 +215,20 @@ static ssize_t name_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct uio_device *idev = dev_get_drvdata(dev);
- return sprintf(buf, "%s\n", idev->info->name);
+ int ret;
+
+ mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ ret = -EINVAL;
+ dev_err(dev, "the device has been unregistered\n");
+ goto out;
+ }
+
+ ret = sprintf(buf, "%s\n", idev->info->name);
+
+out:
+ mutex_unlock(&idev->info_lock);
+ return ret;
}
static DEVICE_ATTR_RO(name);
@@ -223,7 +236,20 @@ static ssize_t version_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct uio_device *idev = dev_get_drvdata(dev);
- return sprintf(buf, "%s\n", idev->info->version);
+ int ret;
+
+ mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ ret = -EINVAL;
+ dev_err(dev, "the device has been unregistered\n");
+ goto out;
+ }
+
+ ret = sprintf(buf, "%s\n", idev->info->version);
+
+out:
+ mutex_unlock(&idev->info_lock);
+ return ret;
}
static DEVICE_ATTR_RO(version);
@@ -399,7 +425,12 @@ static void uio_free_minor(struct uio_device *idev)
*/
void uio_event_notify(struct uio_info *info)
{
- struct uio_device *idev = info->uio_dev;
+ struct uio_device *idev;
+
+ if (!info)
+ return;
+
+ idev = info->uio_dev;
atomic_inc(&idev->event);
wake_up_interruptible(&idev->wait);
@@ -415,11 +446,20 @@ void uio_event_notify(struct uio_info *info)
static irqreturn_t uio_interrupt(int irq, void *dev_id)
{
struct uio_device *idev = (struct uio_device *)dev_id;
- irqreturn_t ret = idev->info->handler(irq, idev->info);
+ irqreturn_t ret;
+
+ mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ ret = IRQ_NONE;
+ goto out;
+ }
+ ret = idev->info->handler(irq, idev->info);
if (ret == IRQ_HANDLED)
uio_event_notify(idev->info);
+out:
+ mutex_unlock(&idev->info_lock);
return ret;
}
@@ -460,6 +500,12 @@ static int uio_open(struct inode *inode, struct file *filep)
filep->private_data = listener;
mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ mutex_unlock(&idev->info_lock);
+ ret = -EINVAL;
+ goto err_alloc_listener;
+ }
+
if (idev->info && idev->info->open)
ret = idev->info->open(idev->info, inode);
mutex_unlock(&idev->info_lock);
@@ -590,6 +636,11 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
s32 irq_on;
mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ retval = -EINVAL;
+ goto out;
+ }
+
if (!idev->info || !idev->info->irq) {
retval = -EIO;
goto out;
@@ -635,10 +686,20 @@ static vm_fault_t uio_vma_fault(struct vm_fault *vmf)
struct page *page;
unsigned long offset;
void *addr;
+ int ret = 0;
+ int mi;
- int mi = uio_find_mem_index(vmf->vma);
- if (mi < 0)
- return VM_FAULT_SIGBUS;
+ mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ ret = VM_FAULT_SIGBUS;
+ goto out;
+ }
+
+ mi = uio_find_mem_index(vmf->vma);
+ if (mi < 0) {
+ ret = VM_FAULT_SIGBUS;
+ goto out;
+ }
/*
* We need to subtract mi because userspace uses offset = N*PAGE_SIZE
@@ -653,7 +714,11 @@ static vm_fault_t uio_vma_fault(struct vm_fault *vmf)
page = vmalloc_to_page(addr);
get_page(page);
vmf->page = page;
- return 0;
+
+out:
+ mutex_unlock(&idev->info_lock);
+
+ return ret;
}
static const struct vm_operations_struct uio_logical_vm_ops = {
@@ -678,6 +743,7 @@ static int uio_mmap_physical(struct vm_area_struct *vma)
struct uio_device *idev = vma->vm_private_data;
int mi = uio_find_mem_index(vma);
struct uio_mem *mem;
+
if (mi < 0)
return -EINVAL;
mem = idev->info->mem + mi;
@@ -719,30 +785,46 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
vma->vm_private_data = idev;
+ mutex_lock(&idev->info_lock);
+ if (!idev->info) {
+ ret = -EINVAL;
+ goto out;
+ }
+
mi = uio_find_mem_index(vma);
- if (mi < 0)
- return -EINVAL;
+ if (mi < 0) {
+ ret = -EINVAL;
+ goto out;
+ }
requested_pages = vma_pages(vma);
actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
- if (requested_pages > actual_pages)
- return -EINVAL;
+ if (requested_pages > actual_pages) {
+ ret = -EINVAL;
+ goto out;
+ }
if (idev->info->mmap) {
ret = idev->info->mmap(idev->info, vma);
- return ret;
+ goto out;
}
switch (idev->info->mem[mi].memtype) {
case UIO_MEM_PHYS:
- return uio_mmap_physical(vma);
+ ret = uio_mmap_physical(vma);
+ break;
case UIO_MEM_LOGICAL:
case UIO_MEM_VIRTUAL:
- return uio_mmap_logical(vma);
+ ret = uio_mmap_logical(vma);
+ break;
default:
- return -EINVAL;
+ ret = -EINVAL;
}
+
+out:
+ mutex_unlock(&idev->info_lock);
+ return 0;
}
static const struct file_operations uio_fops = {
@@ -932,12 +1014,12 @@ void uio_unregister_device(struct uio_info *info)
uio_free_minor(idev);
+ mutex_lock(&idev->info_lock);
uio_dev_del_attributes(idev);
if (info->irq && info->irq != UIO_IRQ_CUSTOM)
free_irq(info->irq, idev);
- mutex_lock(&idev->info_lock);
idev->info = NULL;
mutex_unlock(&idev->info_lock);
--
1.8.3.1
From: Xiubo Li <[email protected]>
We are hitting a regression with the following commit:
commit a93e7b331568227500186a465fee3c2cb5dffd1f
Author: Hamish Martin <[email protected]>
Date: Mon May 14 13:32:23 2018 +1200
uio: Prevent device destruction while fds are open
The problem is the addition of spin_lock_irqsave in uio_write. This
leads to hitting uio_write -> copy_from_user -> _copy_from_user ->
might_fault and the logs filling up with sleeping warnings.
I also noticed some uio drivers allocate memory, sleep, grab mutexes
from callouts like open() and release and uio is now doing
spin_lock_irqsave while calling them.
Reported-by: Mike Christie <[email protected]>
CC: Hamish Martin <[email protected]>
Signed-off-by: Xiubo Li <[email protected]>
---
drivers/uio/uio.c | 32 +++++++++++++-------------------
include/linux/uio_driver.h | 2 +-
2 files changed, 14 insertions(+), 20 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index b4b2ae1..655ade4 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -433,7 +433,6 @@ static int uio_open(struct inode *inode, struct file *filep)
struct uio_device *idev;
struct uio_listener *listener;
int ret = 0;
- unsigned long flags;
mutex_lock(&minor_lock);
idev = idr_find(&uio_idr, iminor(inode));
@@ -460,10 +459,10 @@ static int uio_open(struct inode *inode, struct file *filep)
listener->event_count = atomic_read(&idev->event);
filep->private_data = listener;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (idev->info && idev->info->open)
ret = idev->info->open(idev->info, inode);
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
if (ret)
goto err_infoopen;
@@ -495,12 +494,11 @@ static int uio_release(struct inode *inode, struct file *filep)
int ret = 0;
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (idev->info && idev->info->release)
ret = idev->info->release(idev->info, inode);
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
module_put(idev->owner);
kfree(listener);
@@ -513,12 +511,11 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
struct uio_listener *listener = filep->private_data;
struct uio_device *idev = listener->dev;
__poll_t ret = 0;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq)
ret = -EIO;
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
if (ret)
return ret;
@@ -537,12 +534,11 @@ static ssize_t uio_read(struct file *filep, char __user *buf,
DECLARE_WAITQUEUE(wait, current);
ssize_t retval = 0;
s32 event_count;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq)
retval = -EIO;
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
if (retval)
return retval;
@@ -592,9 +588,8 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
struct uio_device *idev = listener->dev;
ssize_t retval;
s32 irq_on;
- unsigned long flags;
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
if (!idev->info || !idev->info->irq) {
retval = -EIO;
goto out;
@@ -618,7 +613,7 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
retval = idev->info->irqcontrol(idev->info, irq_on);
out:
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
return retval ? retval : sizeof(s32);
}
@@ -865,7 +860,7 @@ int __uio_register_device(struct module *owner,
idev->owner = owner;
idev->info = info;
- spin_lock_init(&idev->info_lock);
+ mutex_init(&idev->info_lock);
init_waitqueue_head(&idev->wait);
atomic_set(&idev->event, 0);
@@ -929,7 +924,6 @@ int __uio_register_device(struct module *owner,
void uio_unregister_device(struct uio_info *info)
{
struct uio_device *idev;
- unsigned long flags;
if (!info || !info->uio_dev)
return;
@@ -943,9 +937,9 @@ void uio_unregister_device(struct uio_info *info)
if (info->irq && info->irq != UIO_IRQ_CUSTOM)
free_irq(info->irq, idev);
- spin_lock_irqsave(&idev->info_lock, flags);
+ mutex_lock(&idev->info_lock);
idev->info = NULL;
- spin_unlock_irqrestore(&idev->info_lock, flags);
+ mutex_unlock(&idev->info_lock);
device_unregister(&idev->dev);
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 6c5f207..6f8b68c 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -75,7 +75,7 @@ struct uio_device {
struct fasync_struct *async_queue;
wait_queue_head_t wait;
struct uio_info *info;
- spinlock_t info_lock;
+ struct mutex info_lock;
struct kobject *map_dir;
struct kobject *portio_dir;
};
--
1.8.3.1
Hi Xiubo,
Thanks for your patch that addresses the regression found with my
earlier commit.
I will take your code and run it in our scenario that showed the bug
that led to my commit. Unfortunately I won't be able to get that done
until mid-next week. I intend to report back to you by July 13th.
Thanks,
Hamish M
On 07/06/2018 02:57 PM, [email protected] wrote:
> From: Xiubo Li <[email protected]>
>
> The V2 patch set maybe not post successfully, so post it again
> with one new updation.
>
> V2:
> - resend it with some small fix
>
> V3:
> - switch to use request_threaded_irq
>
>
> Xiubo Li (3):
> uio: use request_threaded_irq instead
> uio: change to use the mutex lock instead of the spin lock
> uio: fix crash after the device is unregistered
>
> drivers/uio/uio.c | 151 ++++++++++++++++++++++++++++++++++-----------
> include/linux/uio_driver.h | 2 +-
> 2 files changed, 115 insertions(+), 38 deletions(-)
>
Looks ok to me.
Reviewed-by: Hamish Martin <[email protected]>
On 07/06/2018 02:57 PM, [email protected] wrote:
> From: Xiubo Li <[email protected]>
>
> We are hitting a regression with the following commit:
>
> commit a93e7b331568227500186a465fee3c2cb5dffd1f
> Author: Hamish Martin <[email protected]>
> Date: Mon May 14 13:32:23 2018 +1200
>
> uio: Prevent device destruction while fds are open
>
> The problem is the addition of spin_lock_irqsave in uio_write. This
> leads to hitting uio_write -> copy_from_user -> _copy_from_user ->
> might_fault and the logs filling up with sleeping warnings.
>
> I also noticed some uio drivers allocate memory, sleep, grab mutexes
> from callouts like open() and release and uio is now doing
> spin_lock_irqsave while calling them.
>
> Reported-by: Mike Christie <[email protected]>
> CC: Hamish Martin <[email protected]>
> Signed-off-by: Xiubo Li <[email protected]>
> ---
> drivers/uio/uio.c | 32 +++++++++++++-------------------
> include/linux/uio_driver.h | 2 +-
> 2 files changed, 14 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index b4b2ae1..655ade4 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -433,7 +433,6 @@ static int uio_open(struct inode *inode, struct file *filep)
> struct uio_device *idev;
> struct uio_listener *listener;
> int ret = 0;
> - unsigned long flags;
>
> mutex_lock(&minor_lock);
> idev = idr_find(&uio_idr, iminor(inode));
> @@ -460,10 +459,10 @@ static int uio_open(struct inode *inode, struct file *filep)
> listener->event_count = atomic_read(&idev->event);
> filep->private_data = listener;
>
> - spin_lock_irqsave(&idev->info_lock, flags);
> + mutex_lock(&idev->info_lock);
> if (idev->info && idev->info->open)
> ret = idev->info->open(idev->info, inode);
> - spin_unlock_irqrestore(&idev->info_lock, flags);
> + mutex_unlock(&idev->info_lock);
> if (ret)
> goto err_infoopen;
>
> @@ -495,12 +494,11 @@ static int uio_release(struct inode *inode, struct file *filep)
> int ret = 0;
> struct uio_listener *listener = filep->private_data;
> struct uio_device *idev = listener->dev;
> - unsigned long flags;
>
> - spin_lock_irqsave(&idev->info_lock, flags);
> + mutex_lock(&idev->info_lock);
> if (idev->info && idev->info->release)
> ret = idev->info->release(idev->info, inode);
> - spin_unlock_irqrestore(&idev->info_lock, flags);
> + mutex_unlock(&idev->info_lock);
>
> module_put(idev->owner);
> kfree(listener);
> @@ -513,12 +511,11 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
> struct uio_listener *listener = filep->private_data;
> struct uio_device *idev = listener->dev;
> __poll_t ret = 0;
> - unsigned long flags;
>
> - spin_lock_irqsave(&idev->info_lock, flags);
> + mutex_lock(&idev->info_lock);
> if (!idev->info || !idev->info->irq)
> ret = -EIO;
> - spin_unlock_irqrestore(&idev->info_lock, flags);
> + mutex_unlock(&idev->info_lock);
>
> if (ret)
> return ret;
> @@ -537,12 +534,11 @@ static ssize_t uio_read(struct file *filep, char __user *buf,
> DECLARE_WAITQUEUE(wait, current);
> ssize_t retval = 0;
> s32 event_count;
> - unsigned long flags;
>
> - spin_lock_irqsave(&idev->info_lock, flags);
> + mutex_lock(&idev->info_lock);
> if (!idev->info || !idev->info->irq)
> retval = -EIO;
> - spin_unlock_irqrestore(&idev->info_lock, flags);
> + mutex_unlock(&idev->info_lock);
>
> if (retval)
> return retval;
> @@ -592,9 +588,8 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
> struct uio_device *idev = listener->dev;
> ssize_t retval;
> s32 irq_on;
> - unsigned long flags;
>
> - spin_lock_irqsave(&idev->info_lock, flags);
> + mutex_lock(&idev->info_lock);
> if (!idev->info || !idev->info->irq) {
> retval = -EIO;
> goto out;
> @@ -618,7 +613,7 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
> retval = idev->info->irqcontrol(idev->info, irq_on);
>
> out:
> - spin_unlock_irqrestore(&idev->info_lock, flags);
> + mutex_unlock(&idev->info_lock);
> return retval ? retval : sizeof(s32);
> }
>
> @@ -865,7 +860,7 @@ int __uio_register_device(struct module *owner,
>
> idev->owner = owner;
> idev->info = info;
> - spin_lock_init(&idev->info_lock);
> + mutex_init(&idev->info_lock);
> init_waitqueue_head(&idev->wait);
> atomic_set(&idev->event, 0);
>
> @@ -929,7 +924,6 @@ int __uio_register_device(struct module *owner,
> void uio_unregister_device(struct uio_info *info)
> {
> struct uio_device *idev;
> - unsigned long flags;
>
> if (!info || !info->uio_dev)
> return;
> @@ -943,9 +937,9 @@ void uio_unregister_device(struct uio_info *info)
> if (info->irq && info->irq != UIO_IRQ_CUSTOM)
> free_irq(info->irq, idev);
>
> - spin_lock_irqsave(&idev->info_lock, flags);
> + mutex_lock(&idev->info_lock);
> idev->info = NULL;
> - spin_unlock_irqrestore(&idev->info_lock, flags);
> + mutex_unlock(&idev->info_lock);
>
> device_unregister(&idev->dev);
>
> diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
> index 6c5f207..6f8b68c 100644
> --- a/include/linux/uio_driver.h
> +++ b/include/linux/uio_driver.h
> @@ -75,7 +75,7 @@ struct uio_device {
> struct fasync_struct *async_queue;
> wait_queue_head_t wait;
> struct uio_info *info;
> - spinlock_t info_lock;
> + struct mutex info_lock;
> struct kobject *map_dir;
> struct kobject *portio_dir;
> };
Looks ok to me.
Reviewed-by: Hamish Martin <[email protected]>
On 07/06/2018 02:57 PM, [email protected] wrote:
> From: Xiubo Li <[email protected]>
>
> For the target_core_user use case, after the device is unregistered
> it maybe still opened in user space, then the kernel will crash, like:
>
> [ 251.163692] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> [ 251.163820] IP: [<ffffffffc0736213>] show_name+0x23/0x40 [uio]
> [ 251.163965] PGD 8000000062694067 PUD 62696067 PMD 0
> [ 251.164097] Oops: 0000 [#1] SMP
> ...
> [ 251.165605] e1000 mptscsih mptbase drm_panel_orientation_quirks dm_mirror dm_region_hash dm_log dm_mod
> [ 251.166014] CPU: 0 PID: 13380 Comm: tcmu-runner Kdump: loaded Not tainted 3.10.0-916.el7.test.x86_64 #1
> [ 251.166381] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
> [ 251.166747] task: ffff971eb91db0c0 ti: ffff971e9e384000 task.ti: ffff971e9e384000
> [ 251.167137] RIP: 0010:[<ffffffffc0736213>] [<ffffffffc0736213>] show_name+0x23/0x40 [uio]
> [ 251.167563] RSP: 0018:ffff971e9e387dc8 EFLAGS: 00010282
> [ 251.167978] RAX: 0000000000000000 RBX: ffff971e9e3f8000 RCX: ffff971eb8368d98
> [ 251.168408] RDX: ffff971e9e3f8000 RSI: ffffffffc0738084 RDI: ffff971e9e3f8000
> [ 251.168856] RBP: ffff971e9e387dd0 R08: ffff971eb8bc0018 R09: 0000000000000000
> [ 251.169296] R10: 0000000000001000 R11: ffffffffa09d444d R12: ffffffffa1076e80
> [ 251.169750] R13: ffff971e9e387f18 R14: 0000000000000001 R15: ffff971e9cfb1c80
> [ 251.170213] FS: 00007ff37d175880(0000) GS:ffff971ebb600000(0000) knlGS:0000000000000000
> [ 251.170693] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 251.171248] CR2: 0000000000000008 CR3: 00000000001f6000 CR4: 00000000003607f0
> [ 251.172071] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 251.172640] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 251.173236] Call Trace:
> [ 251.173789] [<ffffffffa0c9b2d3>] dev_attr_show+0x23/0x60
> [ 251.174356] [<ffffffffa0f561b2>] ? mutex_lock+0x12/0x2f
> [ 251.174892] [<ffffffffa0ac6d9f>] sysfs_kf_seq_show+0xcf/0x1f0
> [ 251.175433] [<ffffffffa0ac54e6>] kernfs_seq_show+0x26/0x30
> [ 251.175981] [<ffffffffa0a63be0>] seq_read+0x110/0x3f0
> [ 251.176609] [<ffffffffa0ac5d45>] kernfs_fop_read+0xf5/0x160
> [ 251.177158] [<ffffffffa0a3d3af>] vfs_read+0x9f/0x170
> [ 251.177707] [<ffffffffa0a3e27f>] SyS_read+0x7f/0xf0
> [ 251.178268] [<ffffffffa0f648af>] system_call_fastpath+0x1c/0x21
> [ 251.178823] Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 53 48 89 d3 e8 7e 96 56 e0 48 8b 80 d8 02 00 00 48 89 df 48 c7 c6 84 80 73 c0 <48> 8b 50 08 31 c0 e8 e2 67 44 e0 5b 48 98 5d c3 0f 1f 00 66 2e
> [ 251.180115] RIP [<ffffffffc0736213>] show_name+0x23/0x40 [uio]
> [ 251.180820] RSP <ffff971e9e387dc8>
> [ 251.181473] CR2: 0000000000000008
>
> CC: Hamish Martin <[email protected]>
> CC: Mike Christie <[email protected]>
> Signed-off-by: Xiubo Li <[email protected]>
> ---
> drivers/uio/uio.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 99 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 655ade4..a0d926e 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -215,7 +215,20 @@ static ssize_t name_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct uio_device *idev = dev_get_drvdata(dev);
> - return sprintf(buf, "%s\n", idev->info->name);
> + int ret;
> +
> + mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + ret = -EINVAL;
> + dev_err(dev, "the device has been unregistered\n");
> + goto out;
> + }
> +
> + ret = sprintf(buf, "%s\n", idev->info->name);
> +
> +out:
> + mutex_unlock(&idev->info_lock);
> + return ret;
> }
> static DEVICE_ATTR_RO(name);
>
> @@ -223,7 +236,20 @@ static ssize_t version_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct uio_device *idev = dev_get_drvdata(dev);
> - return sprintf(buf, "%s\n", idev->info->version);
> + int ret;
> +
> + mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + ret = -EINVAL;
> + dev_err(dev, "the device has been unregistered\n");
> + goto out;
> + }
> +
> + ret = sprintf(buf, "%s\n", idev->info->version);
> +
> +out:
> + mutex_unlock(&idev->info_lock);
> + return ret;
> }
> static DEVICE_ATTR_RO(version);
>
> @@ -399,7 +425,12 @@ static void uio_free_minor(struct uio_device *idev)
> */
> void uio_event_notify(struct uio_info *info)
> {
> - struct uio_device *idev = info->uio_dev;
> + struct uio_device *idev;
> +
> + if (!info)
> + return;
> +
> + idev = info->uio_dev;
>
> atomic_inc(&idev->event);
> wake_up_interruptible(&idev->wait);
> @@ -415,11 +446,20 @@ void uio_event_notify(struct uio_info *info)
> static irqreturn_t uio_interrupt(int irq, void *dev_id)
> {
> struct uio_device *idev = (struct uio_device *)dev_id;
> - irqreturn_t ret = idev->info->handler(irq, idev->info);
> + irqreturn_t ret;
> +
> + mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + ret = IRQ_NONE;
> + goto out;
> + }
>
> + ret = idev->info->handler(irq, idev->info);
> if (ret == IRQ_HANDLED)
> uio_event_notify(idev->info);
>
> +out:
> + mutex_unlock(&idev->info_lock);
> return ret;
> }
>
> @@ -460,6 +500,12 @@ static int uio_open(struct inode *inode, struct file *filep)
> filep->private_data = listener;
>
> mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + mutex_unlock(&idev->info_lock);
> + ret = -EINVAL;
> + goto err_alloc_listener;
> + }
> +
> if (idev->info && idev->info->open)
> ret = idev->info->open(idev->info, inode);
> mutex_unlock(&idev->info_lock);
> @@ -590,6 +636,11 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
> s32 irq_on;
>
> mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + retval = -EINVAL;
> + goto out;
> + }
> +
> if (!idev->info || !idev->info->irq) {
> retval = -EIO;
> goto out;
> @@ -635,10 +686,20 @@ static vm_fault_t uio_vma_fault(struct vm_fault *vmf)
> struct page *page;
> unsigned long offset;
> void *addr;
> + int ret = 0;
> + int mi;
>
> - int mi = uio_find_mem_index(vmf->vma);
> - if (mi < 0)
> - return VM_FAULT_SIGBUS;
> + mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + ret = VM_FAULT_SIGBUS;
> + goto out;
> + }
> +
> + mi = uio_find_mem_index(vmf->vma);
> + if (mi < 0) {
> + ret = VM_FAULT_SIGBUS;
> + goto out;
> + }
>
> /*
> * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
> @@ -653,7 +714,11 @@ static vm_fault_t uio_vma_fault(struct vm_fault *vmf)
> page = vmalloc_to_page(addr);
> get_page(page);
> vmf->page = page;
> - return 0;
> +
> +out:
> + mutex_unlock(&idev->info_lock);
> +
> + return ret;
> }
>
> static const struct vm_operations_struct uio_logical_vm_ops = {
> @@ -678,6 +743,7 @@ static int uio_mmap_physical(struct vm_area_struct *vma)
> struct uio_device *idev = vma->vm_private_data;
> int mi = uio_find_mem_index(vma);
> struct uio_mem *mem;
> +
> if (mi < 0)
> return -EINVAL;
> mem = idev->info->mem + mi;
> @@ -719,30 +785,46 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
>
> vma->vm_private_data = idev;
>
> + mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> mi = uio_find_mem_index(vma);
> - if (mi < 0)
> - return -EINVAL;
> + if (mi < 0) {
> + ret = -EINVAL;
> + goto out;
> + }
>
> requested_pages = vma_pages(vma);
> actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
> + idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
> - if (requested_pages > actual_pages)
> - return -EINVAL;
> + if (requested_pages > actual_pages) {
> + ret = -EINVAL;
> + goto out;
> + }
>
> if (idev->info->mmap) {
> ret = idev->info->mmap(idev->info, vma);
> - return ret;
> + goto out;
> }
>
> switch (idev->info->mem[mi].memtype) {
> case UIO_MEM_PHYS:
> - return uio_mmap_physical(vma);
> + ret = uio_mmap_physical(vma);
> + break;
> case UIO_MEM_LOGICAL:
> case UIO_MEM_VIRTUAL:
> - return uio_mmap_logical(vma);
> + ret = uio_mmap_logical(vma);
> + break;
> default:
> - return -EINVAL;
> + ret = -EINVAL;
> }
> +
> +out:
> + mutex_unlock(&idev->info_lock);
> + return 0;
> }
>
> static const struct file_operations uio_fops = {
> @@ -932,12 +1014,12 @@ void uio_unregister_device(struct uio_info *info)
>
> uio_free_minor(idev);
>
> + mutex_lock(&idev->info_lock);
> uio_dev_del_attributes(idev);
>
> if (info->irq && info->irq != UIO_IRQ_CUSTOM)
> free_irq(info->irq, idev);
>
> - mutex_lock(&idev->info_lock);
> idev->info = NULL;
> mutex_unlock(&idev->info_lock);
>
On 2018/7/6 11:31, Hamish Martin wrote:
> Hi Xiubo,
>
> Thanks for your patch that addresses the regression found with my
> earlier commit.
>
> I will take your code and run it in our scenario that showed the bug
> that led to my commit. Unfortunately I won't be able to get that done
> until mid-next week. I intend to report back to you by July 13th.
Hi Hamish,
Thanks verrrry much for your quickly review and reply about this. Take
your time :-)
BRs
Xiubo
> Thanks,
> Hamish M
>
> On 07/06/2018 02:57 PM, [email protected] wrote:
>> From: Xiubo Li <[email protected]>
>>
>> The V2 patch set maybe not post successfully, so post it again
>> with one new updation.
>>
>> V2:
>> - resend it with some small fix
>>
>> V3:
>> - switch to use request_threaded_irq
>>
>>
>> Xiubo Li (3):
>> uio: use request_threaded_irq instead
>> uio: change to use the mutex lock instead of the spin lock
>> uio: fix crash after the device is unregistered
>>
>> drivers/uio/uio.c | 151 ++++++++++++++++++++++++++++++++++-----------
>> include/linux/uio_driver.h | 2 +-
>> 2 files changed, 115 insertions(+), 38 deletions(-)
>>
On 07/05/2018 09:57 PM, [email protected] wrote:
> static irqreturn_t uio_interrupt(int irq, void *dev_id)
> {
> struct uio_device *idev = (struct uio_device *)dev_id;
> - irqreturn_t ret = idev->info->handler(irq, idev->info);
> + irqreturn_t ret;
> +
> + mutex_lock(&idev->info_lock);
> + if (!idev->info) {
> + ret = IRQ_NONE;
> + goto out;
> + }
>
> + ret = idev->info->handler(irq, idev->info);
> if (ret == IRQ_HANDLED)
> uio_event_notify(idev->info);
>
> +out:
> + mutex_unlock(&idev->info_lock);
> return ret;
> }
Do you need the interrupt related changes in this patch and the first
one? When we do uio_unregister_device -> free_irq does free_irq return
when there are no longer running interrupt handlers that we requested?
If that is not the case then I think we can hit a similar bug. We do:
__uio_register_device -> device_register -> device's refcount goes to
zero so we do -> uio_device_release -> kfree(idev)
and if it is possible the interrupt handler could still run after
free_irq then we would end up doing:
uio_interrupt -> mutex_lock(&idev->info_lock) -> idev access freed memory.
On 07/05/2018 09:57 PM, [email protected] wrote:
> void uio_event_notify(struct uio_info *info)
> {
> - struct uio_device *idev = info->uio_dev;
> + struct uio_device *idev;
> +
> + if (!info)
> + return;
> +
> + idev = info->uio_dev;
>
For this one too, I am not sure if it is needed.
uio_interrupt -> uio_event_notify. See other mail.
driver XYZ -> uio_event_notify. I think drivers need to handle this and
set some bits and/or perform some cleanup to make sure they are not
calling uio_event_notify after it has called uio_unregister_device. The
problem with the above test is if they do not they could have called
uio_unregister_device right after the info test so you could still hit
the problem.
On 2018/7/7 2:23, Mike Christie wrote:
> On 07/05/2018 09:57 PM, [email protected] wrote:
>> static irqreturn_t uio_interrupt(int irq, void *dev_id)
>> {
>> struct uio_device *idev = (struct uio_device *)dev_id;
>> - irqreturn_t ret = idev->info->handler(irq, idev->info);
>> + irqreturn_t ret;
>> +
>> + mutex_lock(&idev->info_lock);
>> + if (!idev->info) {
>> + ret = IRQ_NONE;
>> + goto out;
>> + }
>>
>> + ret = idev->info->handler(irq, idev->info);
>> if (ret == IRQ_HANDLED)
>> uio_event_notify(idev->info);
>>
>> +out:
>> + mutex_unlock(&idev->info_lock);
>> return ret;
>> }
>
> Do you need the interrupt related changes in this patch and the first
> one?
Actually, the NULL checking is not a must, we can remove this. But the
lock/unlock is needed.
> When we do uio_unregister_device -> free_irq does free_irq return
> when there are no longer running interrupt handlers that we requested?
>
> If that is not the case then I think we can hit a similar bug. We do:
>
> __uio_register_device -> device_register -> device's refcount goes to
> zero so we do -> uio_device_release -> kfree(idev)
>
> and if it is possible the interrupt handler could still run after
> free_irq then we would end up doing:
>
> uio_interrupt -> mutex_lock(&idev->info_lock) -> idev access freed memory.
I think this shouldn't happen. Because the free_irq function does not
return until any executing interrupts for this IRQ have completed.
Thanks,
BRs
On 2018/7/7 2:58, Mike Christie wrote:
> On 07/05/2018 09:57 PM, [email protected] wrote:
>> void uio_event_notify(struct uio_info *info)
>> {
>> - struct uio_device *idev = info->uio_dev;
>> + struct uio_device *idev;
>> +
>> + if (!info)
>> + return;
>> +
>> + idev = info->uio_dev;
>>
> For this one too, I am not sure if it is needed.
>
> uio_interrupt -> uio_event_notify. See other mail.
>
> driver XYZ -> uio_event_notify. I think drivers need to handle this and
> set some bits and/or perform some cleanup to make sure they are not
> calling uio_event_notify after it has called uio_unregister_device. The
> problem with the above test is if they do not they could have called
> uio_unregister_device right after the info test so you could still hit
> the problem.
When we are tcmu_destroy_device(), if the netlink notify event to
userspace is not successful then the TCMU will call the uio unregister,
which will set the idev->info = NULL, without close and deleting the
device in userspace. But the TCMU could still queue cmds to the ring
buffer, then the uio_event_notify will be called.
For this case only when using idev->info it would happen. And currently
there is no need to check this, I will remove it for now.
Thanks,
BRs
On 07/06/2018 08:47 PM, Xiubo Li wrote:
> On 2018/7/7 2:58, Mike Christie wrote:
>> On 07/05/2018 09:57 PM, [email protected] wrote:
>>> void uio_event_notify(struct uio_info *info)
>>> {
>>> - struct uio_device *idev = info->uio_dev;
>>> + struct uio_device *idev;
>>> +
>>> + if (!info)
>>> + return;
>>> +
>>> + idev = info->uio_dev;
>>>
>> For this one too, I am not sure if it is needed.
>>
>> uio_interrupt -> uio_event_notify. See other mail.
>>
>> driver XYZ -> uio_event_notify. I think drivers need to handle this and
>> set some bits and/or perform some cleanup to make sure they are not
>> calling uio_event_notify after it has called uio_unregister_device. The
>> problem with the above test is if they do not they could have called
>> uio_unregister_device right after the info test so you could still hit
>> the problem.
>
> When we are tcmu_destroy_device(), if the netlink notify event to
> userspace is not successful then the TCMU will call the uio unregister,
> which will set the idev->info = NULL, without close and deleting the
> device in userspace. But the TCMU could still queue cmds to the ring
> buffer, then the uio_event_notify will be called.
Before tcmu_destroy_device is called LIO will have stopped new IO and
waited for outstanding IO to be completed, so it would never be called
after uio_unregister_device. If it does, it's a bug in LIO.
On 07/06/2018 08:28 PM, Xiubo Li wrote:
> On 2018/7/7 2:23, Mike Christie wrote:
>> On 07/05/2018 09:57 PM, [email protected] wrote:
>>> static irqreturn_t uio_interrupt(int irq, void *dev_id)
>>> {
>>> struct uio_device *idev = (struct uio_device *)dev_id;
>>> - irqreturn_t ret = idev->info->handler(irq, idev->info);
>>> + irqreturn_t ret;
>>> +
>>> + mutex_lock(&idev->info_lock);
>>> + if (!idev->info) {
>>> + ret = IRQ_NONE;
>>> + goto out;
>>> + }
>>> + ret = idev->info->handler(irq, idev->info);
>>> if (ret == IRQ_HANDLED)
>>> uio_event_notify(idev->info);
>>> +out:
>>> + mutex_unlock(&idev->info_lock);
>>> return ret;
>>> }
>>
>> Do you need the interrupt related changes in this patch and the first
>> one?
> Actually, the NULL checking is not a must, we can remove this. But the
> lock/unlock is needed.
>> When we do uio_unregister_device -> free_irq does free_irq return
>> when there are no longer running interrupt handlers that we requested?
>>
>> If that is not the case then I think we can hit a similar bug. We do:
>>
>> __uio_register_device -> device_register -> device's refcount goes to
>> zero so we do -> uio_device_release -> kfree(idev)
>>
>> and if it is possible the interrupt handler could still run after
>> free_irq then we would end up doing:
>>
>> uio_interrupt -> mutex_lock(&idev->info_lock) -> idev access freed
>> memory.
>
> I think this shouldn't happen. Because the free_irq function does not
> return until any executing interrupts for this IRQ have completed.
>
If free_irq returns after executing interrupts and does not allow new
executions what is the lock protecting in uio_interrupt?
On 2018/7/10 0:40, Mike Christie wrote:
> On 07/06/2018 08:47 PM, Xiubo Li wrote:
>> On 2018/7/7 2:58, Mike Christie wrote:
>>> On 07/05/2018 09:57 PM, [email protected] wrote:
>>>> void uio_event_notify(struct uio_info *info)
>>>> {
>>>> - struct uio_device *idev = info->uio_dev;
>>>> + struct uio_device *idev;
>>>> +
>>>> + if (!info)
>>>> + return;
>>>> +
>>>> + idev = info->uio_dev;
>>>>
>>> For this one too, I am not sure if it is needed.
>>>
>>> uio_interrupt -> uio_event_notify. See other mail.
>>>
>>> driver XYZ -> uio_event_notify. I think drivers need to handle this and
>>> set some bits and/or perform some cleanup to make sure they are not
>>> calling uio_event_notify after it has called uio_unregister_device. The
>>> problem with the above test is if they do not they could have called
>>> uio_unregister_device right after the info test so you could still hit
>>> the problem.
>> When we are tcmu_destroy_device(), if the netlink notify event to
>> userspace is not successful then the TCMU will call the uio unregister,
>> which will set the idev->info = NULL, without close and deleting the
>> device in userspace. But the TCMU could still queue cmds to the ring
>> buffer, then the uio_event_notify will be called.
> Before tcmu_destroy_device is called LIO will have stopped new IO and
> waited for outstanding IO to be completed, so it would never be called
> after uio_unregister_device. If it does, it's a bug in LIO.
Yeah, So this should be fixed now. Only hit one crash seem related to
uio of this code with lower kernel before.
Thanks,
BRs
On 2018/7/10 1:06, Mike Christie wrote:
> On 07/06/2018 08:28 PM, Xiubo Li wrote:
>> On 2018/7/7 2:23, Mike Christie wrote:
>>> On 07/05/2018 09:57 PM, [email protected] wrote:
>>>> static irqreturn_t uio_interrupt(int irq, void *dev_id)
>>>> {
>>>> struct uio_device *idev = (struct uio_device *)dev_id;
>>>> - irqreturn_t ret = idev->info->handler(irq, idev->info);
>>>> + irqreturn_t ret;
>>>> +
>>>> + mutex_lock(&idev->info_lock);
>>>> + if (!idev->info) {
>>>> + ret = IRQ_NONE;
>>>> + goto out;
>>>> + }
>>>> + ret = idev->info->handler(irq, idev->info);
>>>> if (ret == IRQ_HANDLED)
>>>> uio_event_notify(idev->info);
>>>> +out:
>>>> + mutex_unlock(&idev->info_lock);
>>>> return ret;
>>>> }
>>> Do you need the interrupt related changes in this patch and the first
>>> one?
>> Actually, the NULL checking is not a must, we can remove this. But the
>> lock/unlock is needed.
>>> When we do uio_unregister_device -> free_irq does free_irq return
>>> when there are no longer running interrupt handlers that we requested?
>>>
>>> If that is not the case then I think we can hit a similar bug. We do:
>>>
>>> __uio_register_device -> device_register -> device's refcount goes to
>>> zero so we do -> uio_device_release -> kfree(idev)
>>>
>>> and if it is possible the interrupt handler could still run after
>>> free_irq then we would end up doing:
>>>
>>> uio_interrupt -> mutex_lock(&idev->info_lock) -> idev access freed
>>> memory.
>> I think this shouldn't happen. Because the free_irq function does not
>> return until any executing interrupts for this IRQ have completed.
>>
> If free_irq returns after executing interrupts and does not allow new
> executions what is the lock protecting in uio_interrupt?
>
I meant idev->info->handler(irq, idev->info), it may should be protected
by the related lock in each driver.
Thanks，