* [PATCH] rnbd: fix compilation error when CONFIG_MODULES is disabled
[not found] <86962843-e786-4a3f-0b85-1e06fbdbd76a@infradead.org>
@ 2020-05-21 17:50 ` Danil Kipnis
2020-05-21 18:39 ` Randy Dunlap
0 siblings, 1 reply; 4+ messages in thread
From: Danil Kipnis @ 2020-05-21 17:50 UTC (permalink / raw)
To: linux-block, linux-rdma, dledford, jgg
Cc: axboe, bvanassche, leon, danil.kipnis, jinpu.wang, guoqing.jiang,
Randy Dunlap
module_is_live function is only defined when CONFIG_MODULES is enabled.
Use try_module_get instead to check whether the module is being removed.
When module unload and manuall unmapping is happening in parallel, we can
try removing the symlink twice: rnbd_client_exit vs. rnbd_clt_unmap_dev_store.
This is probably not the best way to deal with this race in general, but for
now this fixes the compilation issue when CONFIG_MODULES is disabled and has
no functional impact. Regression tests passed.
Fixes: 1eb54f8f5dd8 block/rnbd: client: sysfs interface functions
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Suggested-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
---
drivers/block/rnbd/rnbd-clt-sysfs.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
index a4508fcc7ffe..73d7cb40abb3 100644
--- a/drivers/block/rnbd/rnbd-clt-sysfs.c
+++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
@@ -428,12 +428,14 @@ static struct attribute *rnbd_dev_attrs[] = {
void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
{
/*
- * The module_is_live() check is crucial and helps to avoid annoying
- * sysfs warning raised in sysfs_remove_link(), when the whole sysfs
- * path was just removed, see rnbd_close_sessions().
+ * The module unload rnbd_client_exit path is racing with unmapping of the
+ * last single device from the sysfs manually i.e. rnbd_clt_unmap_dev_store()
+ * leading to a sysfs warning because of sysfs link already was removed already.
*/
- if (strlen(dev->blk_symlink_name) && module_is_live(THIS_MODULE))
+ if (strlen(dev->blk_symlink_name) && try_module_get(THIS_MODULE)) {
sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
+ module_put(THIS_MODULE);
+ }
}
static struct kobj_type rnbd_dev_ktype = {
base-commit: f11e0ec55f0c80ff47693af2150bad5db0e20387
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] rnbd: fix compilation error when CONFIG_MODULES is disabled
2020-05-21 17:50 ` [PATCH] rnbd: fix compilation error when CONFIG_MODULES is disabled Danil Kipnis
@ 2020-05-21 18:39 ` Randy Dunlap
2020-05-21 18:59 ` Danil Kipnis
0 siblings, 1 reply; 4+ messages in thread
From: Randy Dunlap @ 2020-05-21 18:39 UTC (permalink / raw)
To: Danil Kipnis, linux-block, linux-rdma, dledford, jgg
Cc: axboe, bvanassche, leon, jinpu.wang, guoqing.jiang
On 5/21/20 10:50 AM, Danil Kipnis wrote:
> module_is_live function is only defined when CONFIG_MODULES is enabled.
> Use try_module_get instead to check whether the module is being removed.
>
> When module unload and manuall unmapping is happening in parallel, we can
> try removing the symlink twice: rnbd_client_exit vs. rnbd_clt_unmap_dev_store.
>
> This is probably not the best way to deal with this race in general, but for
> now this fixes the compilation issue when CONFIG_MODULES is disabled and has
> no functional impact. Regression tests passed.
>
> Fixes: 1eb54f8f5dd8 block/rnbd: client: sysfs interface functions
The Fixes: line has a specific expected format. It should be like this:
Fixes: 1eb54f8f5dd8 ("block/rnbd: client: sysfs interface functions")
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Suggested-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
> Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Thanks.
> ---
> drivers/block/rnbd/rnbd-clt-sysfs.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
> index a4508fcc7ffe..73d7cb40abb3 100644
> --- a/drivers/block/rnbd/rnbd-clt-sysfs.c
> +++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
> @@ -428,12 +428,14 @@ static struct attribute *rnbd_dev_attrs[] = {
> void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
> {
> /*
> - * The module_is_live() check is crucial and helps to avoid annoying
> - * sysfs warning raised in sysfs_remove_link(), when the whole sysfs
> - * path was just removed, see rnbd_close_sessions().
> + * The module unload rnbd_client_exit path is racing with unmapping of the
> + * last single device from the sysfs manually i.e. rnbd_clt_unmap_dev_store()
> + * leading to a sysfs warning because of sysfs link already was removed already.
> */
> - if (strlen(dev->blk_symlink_name) && module_is_live(THIS_MODULE))
> + if (strlen(dev->blk_symlink_name) && try_module_get(THIS_MODULE)) {
> sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
> + module_put(THIS_MODULE);
> + }
> }
>
> static struct kobj_type rnbd_dev_ktype = {
>
> base-commit: f11e0ec55f0c80ff47693af2150bad5db0e20387
>
--
~Randy
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] rnbd: fix compilation error when CONFIG_MODULES is disabled
2020-05-21 18:39 ` Randy Dunlap
@ 2020-05-21 18:59 ` Danil Kipnis
2020-05-23 0:24 ` Jason Gunthorpe
0 siblings, 1 reply; 4+ messages in thread
From: Danil Kipnis @ 2020-05-21 18:59 UTC (permalink / raw)
To: linux-block, linux-rdma, dledford, jgg, rdunlap
Cc: axboe, bvanassche, leon, danil.kipnis, jinpu.wang, guoqing.jiang
module_is_live function is only defined when CONFIG_MODULES is enabled.
Use try_module_get instead to check whether the module is being removed.
When module unload and manuall unmapping is happening in parallel, we can
try removing the symlink twice: rnbd_client_exit vs. rnbd_clt_unmap_dev_store.
This is probably not the best way to deal with this race in general, but for
now this fixes the compilation issue when CONFIG_MODULES is disabled and has
no functional impact. Regression tests passed.
Fixes: 1eb54f8f5dd8 ("block/rnbd: client: sysfs interface functions")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Suggested-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
---
v1->v2 Fix format of the "Fixes:" line
Add Acked-by Randy Runlap <rdunlap@infradead.org>
drivers/block/rnbd/rnbd-clt-sysfs.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
index a4508fcc7ffe..73d7cb40abb3 100644
--- a/drivers/block/rnbd/rnbd-clt-sysfs.c
+++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
@@ -428,12 +428,14 @@ static struct attribute *rnbd_dev_attrs[] = {
void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
{
/*
- * The module_is_live() check is crucial and helps to avoid annoying
- * sysfs warning raised in sysfs_remove_link(), when the whole sysfs
- * path was just removed, see rnbd_close_sessions().
+ * The module unload rnbd_client_exit path is racing with unmapping of the
+ * last single device from the sysfs manually i.e. rnbd_clt_unmap_dev_store()
+ * leading to a sysfs warning because of sysfs link already was removed already.
*/
- if (strlen(dev->blk_symlink_name) && module_is_live(THIS_MODULE))
+ if (strlen(dev->blk_symlink_name) && try_module_get(THIS_MODULE)) {
sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
+ module_put(THIS_MODULE);
+ }
}
static struct kobj_type rnbd_dev_ktype = {
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] rnbd: fix compilation error when CONFIG_MODULES is disabled
2020-05-21 18:59 ` Danil Kipnis
@ 2020-05-23 0:24 ` Jason Gunthorpe
0 siblings, 0 replies; 4+ messages in thread
From: Jason Gunthorpe @ 2020-05-23 0:24 UTC (permalink / raw)
To: Danil Kipnis
Cc: linux-block, linux-rdma, dledford, rdunlap, axboe, bvanassche,
leon, jinpu.wang, guoqing.jiang
On Thu, May 21, 2020 at 08:59:09PM +0200, Danil Kipnis wrote:
> module_is_live function is only defined when CONFIG_MODULES is enabled.
> Use try_module_get instead to check whether the module is being removed.
>
> When module unload and manuall unmapping is happening in parallel, we can
> try removing the symlink twice: rnbd_client_exit vs. rnbd_clt_unmap_dev_store.
>
> This is probably not the best way to deal with this race in general, but for
> now this fixes the compilation issue when CONFIG_MODULES is disabled and has
> no functional impact. Regression tests passed.
>
> Fixes: 1eb54f8f5dd8 ("block/rnbd: client: sysfs interface functions")
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Suggested-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
> Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
> Acked-by: Randy Dunlap <rdunlap@infradead.org>
> v1->v2 Fix format of the "Fixes:" line
> Add Acked-by Randy Runlap <rdunlap@infradead.org>
> drivers/block/rnbd/rnbd-clt-sysfs.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
> index a4508fcc7ffe..73d7cb40abb3 100644
> +++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
> @@ -428,12 +428,14 @@ static struct attribute *rnbd_dev_attrs[] = {
> void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
> {
> /*
> - * The module_is_live() check is crucial and helps to avoid annoying
> - * sysfs warning raised in sysfs_remove_link(), when the whole sysfs
> - * path was just removed, see rnbd_close_sessions().
> + * The module unload rnbd_client_exit path is racing with unmapping of the
> + * last single device from the sysfs manually i.e. rnbd_clt_unmap_dev_store()
> + * leading to a sysfs warning because of sysfs link already was removed already.
> */
> - if (strlen(dev->blk_symlink_name) && module_is_live(THIS_MODULE))
> + if (strlen(dev->blk_symlink_name) && try_module_get(THIS_MODULE)) {
> sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
> + module_put(THIS_MODULE);
> + }
> }
This is a really gross thing to do, please fix it properly in future
Applied to for-next
Jason
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-05-21 17:50 ` [PATCH] rnbd: fix compilation error when CONFIG_MODULES is disabled Danil Kipnis
2020-05-21 18:39 ` Randy Dunlap
2020-05-21 18:59 ` Danil Kipnis
2020-05-23 0:24 ` Jason Gunthorpe
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