| Message ID | 20200521185909.457245-1-danil.kipnis@cloud.ionos.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Jason Gunthorpe |
| Headers | show |
| Series | rnbd: fix compilation error when CONFIG_MODULES is disabled | expand |
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
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 = {
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(-)