* [PATCH v2] btrfs: slience the sparse warn of rcu_string
@ 2022-08-24 5:12 Wang Yugui
2022-08-24 7:25 ` Anand Jain
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Wang Yugui @ 2022-08-24 5:12 UTC (permalink / raw)
To: linux-btrfs; +Cc: Wang Yugui, Johannes Thumshirn
slience the sparse warn of rcu_string reported by 'make C=1'
warning example:
fs/btrfs/volumes.c:2300:41: warning: incorrect type in argument 3 (different address spaces)
fs/btrfs/volumes.c:2300:41: expected char const *device_path
fs/btrfs/volumes.c:2300:41: got char [noderef] __rcu *
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Wang Yugui <wangyugui@e16-tech.com>
---
changes since v1:
add a warn example.
add 'Reviewed-by: Johannes Thumshirn'.
fs/btrfs/dev-replace.c | 2 +-
fs/btrfs/volumes.c | 14 +++++++-------
2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 70d001d..b30930e 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -1006,7 +1006,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
btrfs_sysfs_update_devid(tgt_device);
if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &src_device->dev_state))
btrfs_scratch_superblocks(fs_info, src_device->bdev,
- src_device->name->str);
+ rcu_str_deref(src_device->name));
/* write back the superblocks */
trans = btrfs_start_transaction(root, 0);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9481108..2cd261c 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -390,7 +390,7 @@ static struct btrfs_fs_devices *alloc_fs_devices(const u8 *fsid,
void btrfs_free_device(struct btrfs_device *device)
{
WARN_ON(!list_empty(&device->post_commit_list));
- rcu_string_free(device->name);
+ rcu_string_free(rcu_dereference(device->name));
extent_io_tree_release(&device->alloc_state);
btrfs_destroy_dev_zone_info(device);
kfree(device);
@@ -640,7 +640,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
if (!device->name)
return -EINVAL;
- ret = btrfs_get_bdev_and_sb(device->name->str, flags, holder, 1,
+ ret = btrfs_get_bdev_and_sb(rcu_str_deref(device->name), flags, holder, 1,
&bdev, &disk_super);
if (ret)
return ret;
@@ -908,7 +908,7 @@ static noinline struct btrfs_device *device_list_add(const char *path,
disk_super->fsid, devid, found_transid, path,
current->comm, task_pid_nr(current));
- } else if (!device->name || strcmp(device->name->str, path)) {
+ } else if (!device->name || strcmp(rcu_str_deref(device->name), path)) {
/*
* When FS is already mounted.
* 1. If you are here and if the device->name is NULL that
@@ -978,7 +978,7 @@ static noinline struct btrfs_device *device_list_add(const char *path,
mutex_unlock(&fs_devices->device_list_mutex);
return ERR_PTR(-ENOMEM);
}
- rcu_string_free(device->name);
+ rcu_string_free(rcu_dereference(device->name));
rcu_assign_pointer(device->name, name);
if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
fs_devices->missing_devices--;
@@ -1035,7 +1035,7 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
* uuid mutex so nothing we touch in here is going to disappear.
*/
if (orig_dev->name) {
- name = rcu_string_strdup(orig_dev->name->str,
+ name = rcu_string_strdup(rcu_str_deref(orig_dev->name),
GFP_KERNEL);
if (!name) {
btrfs_free_device(device);
@@ -2217,7 +2217,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
*/
if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
btrfs_scratch_superblocks(fs_info, device->bdev,
- device->name->str);
+ rcu_str_deref(device->name));
if (device->bdev) {
sync_blockdev(device->bdev);
invalidate_bdev(device->bdev);
@@ -2332,7 +2332,7 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
mutex_unlock(&fs_devices->device_list_mutex);
btrfs_scratch_superblocks(tgtdev->fs_info, tgtdev->bdev,
- tgtdev->name->str);
+ rcu_str_deref(tgtdev->name));
btrfs_close_bdev(tgtdev);
synchronize_rcu();
--
2.36.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v2] btrfs: slience the sparse warn of rcu_string
2022-08-24 5:12 [PATCH v2] btrfs: slience the sparse warn of rcu_string Wang Yugui
@ 2022-08-24 7:25 ` Anand Jain
2022-09-02 13:55 ` David Sterba
2022-09-05 3:57 ` Wang Yugui
2 siblings, 0 replies; 5+ messages in thread
From: Anand Jain @ 2022-08-24 7:25 UTC (permalink / raw)
To: Wang Yugui, linux-btrfs; +Cc: Johannes Thumshirn
On 8/24/22 13:12, Wang Yugui wrote:
> slience the sparse warn of rcu_string reported by 'make C=1'
>
> warning example:
> fs/btrfs/volumes.c:2300:41: warning: incorrect type in argument 3 (different address spaces)
> fs/btrfs/volumes.c:2300:41: expected char const *device_path
> fs/btrfs/volumes.c:2300:41: got char [noderef] __rcu *
>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Signed-off-by: Wang Yugui <wangyugui@e16-tech.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] btrfs: slience the sparse warn of rcu_string
2022-08-24 5:12 [PATCH v2] btrfs: slience the sparse warn of rcu_string Wang Yugui
2022-08-24 7:25 ` Anand Jain
@ 2022-09-02 13:55 ` David Sterba
2022-09-05 3:57 ` Wang Yugui
2 siblings, 0 replies; 5+ messages in thread
From: David Sterba @ 2022-09-02 13:55 UTC (permalink / raw)
To: Wang Yugui; +Cc: linux-btrfs, Johannes Thumshirn
On Wed, Aug 24, 2022 at 01:12:08PM +0800, Wang Yugui wrote:
> slience the sparse warn of rcu_string reported by 'make C=1'
>
> warning example:
> fs/btrfs/volumes.c:2300:41: warning: incorrect type in argument 3 (different address spaces)
> fs/btrfs/volumes.c:2300:41: expected char const *device_path
> fs/btrfs/volumes.c:2300:41: got char [noderef] __rcu *
>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Signed-off-by: Wang Yugui <wangyugui@e16-tech.com>
With an updated changelog added to misc-next, thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] btrfs: slience the sparse warn of rcu_string
2022-08-24 5:12 [PATCH v2] btrfs: slience the sparse warn of rcu_string Wang Yugui
2022-08-24 7:25 ` Anand Jain
2022-09-02 13:55 ` David Sterba
@ 2022-09-05 3:57 ` Wang Yugui
2022-09-05 15:34 ` David Sterba
2 siblings, 1 reply; 5+ messages in thread
From: Wang Yugui @ 2022-09-05 3:57 UTC (permalink / raw)
To: linux-btrfs
Hi,
> slience the sparse warn of rcu_string reported by 'make C=1'
>
> warning example:
> fs/btrfs/volumes.c:2300:41: warning: incorrect type in argument 3 (different address spaces)
> fs/btrfs/volumes.c:2300:41: expected char const *device_path
> fs/btrfs/volumes.c:2300:41: got char [noderef] __rcu *
I'm sorry that some new WARNING is triggered when
lockdep(CONFIG_PROVE_LOCKING/...) check is enabled.
[ 112.742722] =============================
[ 112.746835] WARNING: suspicious RCU usage
[ 112.750917] 6.0.0-4.0.el7.x86_64 #1 Not tainted
[ 112.755540] -----------------------------
[ 112.759624] fs/btrfs/volumes.c:918 suspicious rcu_dereference_check() usage!
[ 112.766776]
other info that might help us debug this:
[ 112.774921]
rcu_scheduler_active = 2, debug_locks = 1
[ 112.781566] 2 locks held by mount/1725:
[ 112.785471] #0: ffffffffc50592a8 (uuid_mutex){+.+.}-{3:3}, at: btrfs_mount_root+0xfe/0x520 [btrfs]
[ 112.794763] #1: ffffa1147bf068e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: device_list_add+0x28d/0x830 [btrfs]
The fix is yet not clear, we may need rcu_read_lock() just like
3181faa85bda3dc3f5e630a1846526c9caaa38e3 (cfq-iosched: fix a rcu warning)
Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2022/09/05
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Signed-off-by: Wang Yugui <wangyugui@e16-tech.com>
> ---
> changes since v1:
> add a warn example.
> add 'Reviewed-by: Johannes Thumshirn'.
>
> fs/btrfs/dev-replace.c | 2 +-
> fs/btrfs/volumes.c | 14 +++++++-------
> 2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
> index 70d001d..b30930e 100644
> --- a/fs/btrfs/dev-replace.c
> +++ b/fs/btrfs/dev-replace.c
> @@ -1006,7 +1006,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
> btrfs_sysfs_update_devid(tgt_device);
> if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &src_device->dev_state))
> btrfs_scratch_superblocks(fs_info, src_device->bdev,
> - src_device->name->str);
> + rcu_str_deref(src_device->name));
>
> /* write back the superblocks */
> trans = btrfs_start_transaction(root, 0);
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 9481108..2cd261c 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -390,7 +390,7 @@ static struct btrfs_fs_devices *alloc_fs_devices(const u8 *fsid,
> void btrfs_free_device(struct btrfs_device *device)
> {
> WARN_ON(!list_empty(&device->post_commit_list));
> - rcu_string_free(device->name);
> + rcu_string_free(rcu_dereference(device->name));
> extent_io_tree_release(&device->alloc_state);
> btrfs_destroy_dev_zone_info(device);
> kfree(device);
> @@ -640,7 +640,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
> if (!device->name)
> return -EINVAL;
>
> - ret = btrfs_get_bdev_and_sb(device->name->str, flags, holder, 1,
> + ret = btrfs_get_bdev_and_sb(rcu_str_deref(device->name), flags, holder, 1,
> &bdev, &disk_super);
> if (ret)
> return ret;
> @@ -908,7 +908,7 @@ static noinline struct btrfs_device *device_list_add(const char *path,
> disk_super->fsid, devid, found_transid, path,
> current->comm, task_pid_nr(current));
>
> - } else if (!device->name || strcmp(device->name->str, path)) {
> + } else if (!device->name || strcmp(rcu_str_deref(device->name), path)) {
> /*
> * When FS is already mounted.
> * 1. If you are here and if the device->name is NULL that
> @@ -978,7 +978,7 @@ static noinline struct btrfs_device *device_list_add(const char *path,
> mutex_unlock(&fs_devices->device_list_mutex);
> return ERR_PTR(-ENOMEM);
> }
> - rcu_string_free(device->name);
> + rcu_string_free(rcu_dereference(device->name));
> rcu_assign_pointer(device->name, name);
> if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
> fs_devices->missing_devices--;
> @@ -1035,7 +1035,7 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
> * uuid mutex so nothing we touch in here is going to disappear.
> */
> if (orig_dev->name) {
> - name = rcu_string_strdup(orig_dev->name->str,
> + name = rcu_string_strdup(rcu_str_deref(orig_dev->name),
> GFP_KERNEL);
> if (!name) {
> btrfs_free_device(device);
> @@ -2217,7 +2217,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
> */
> if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
> btrfs_scratch_superblocks(fs_info, device->bdev,
> - device->name->str);
> + rcu_str_deref(device->name));
> if (device->bdev) {
> sync_blockdev(device->bdev);
> invalidate_bdev(device->bdev);
> @@ -2332,7 +2332,7 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
> mutex_unlock(&fs_devices->device_list_mutex);
>
> btrfs_scratch_superblocks(tgtdev->fs_info, tgtdev->bdev,
> - tgtdev->name->str);
> + rcu_str_deref(tgtdev->name));
>
> btrfs_close_bdev(tgtdev);
> synchronize_rcu();
> --
> 2.36.2
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v2] btrfs: slience the sparse warn of rcu_string
2022-09-05 3:57 ` Wang Yugui
@ 2022-09-05 15:34 ` David Sterba
0 siblings, 0 replies; 5+ messages in thread
From: David Sterba @ 2022-09-05 15:34 UTC (permalink / raw)
To: Wang Yugui; +Cc: linux-btrfs
On Mon, Sep 05, 2022 at 11:57:26AM +0800, Wang Yugui wrote:
> Hi,
>
> > slience the sparse warn of rcu_string reported by 'make C=1'
> >
> > warning example:
> > fs/btrfs/volumes.c:2300:41: warning: incorrect type in argument 3 (different address spaces)
> > fs/btrfs/volumes.c:2300:41: expected char const *device_path
> > fs/btrfs/volumes.c:2300:41: got char [noderef] __rcu *
>
> I'm sorry that some new WARNING is triggered when
> lockdep(CONFIG_PROVE_LOCKING/...) check is enabled.
>
> [ 112.742722] =============================
> [ 112.746835] WARNING: suspicious RCU usage
> [ 112.750917] 6.0.0-4.0.el7.x86_64 #1 Not tainted
> [ 112.755540] -----------------------------
> [ 112.759624] fs/btrfs/volumes.c:918 suspicious rcu_dereference_check() usage!
> [ 112.766776]
> other info that might help us debug this:
>
> [ 112.774921]
> rcu_scheduler_active = 2, debug_locks = 1
> [ 112.781566] 2 locks held by mount/1725:
> [ 112.785471] #0: ffffffffc50592a8 (uuid_mutex){+.+.}-{3:3}, at: btrfs_mount_root+0xfe/0x520 [btrfs]
> [ 112.794763] #1: ffffa1147bf068e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: device_list_add+0x28d/0x830 [btrfs]
>
>
> The fix is yet not clear, we may need rcu_read_lock() just like
> 3181faa85bda3dc3f5e630a1846526c9caaa38e3 (cfq-iosched: fix a rcu warning)
There are probably more instances that would need the rcu lock/unlock,
eg. in btrfs_open_one_device, btrfs_dev_replace_finishing,
btrfs_destroy_dev_replace_tgtdev, btrfs_rm_device, clone_fs_devices,
device_list_add, btrfs_open_one_device where the dereference is done in
parameter list.
There's one dereference in the message helpers but not using the _in_rcu
variant:
zoned.c:
1403 case BLK_ZONE_COND_READONLY:
1404 btrfs_err(fs_info,
1405 "zoned: offline/readonly zone %llu on device %s (devid %llu)",
1406 physical[i] >> device->zone_info->zone_size_shift,
1407 rcu_str_deref(device->name), device->devid);
We can keep the the patch in for-next and add the missing annotations as
they appear, updating the patch so it may take some time but we'll fix
all the warnings eventually.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-09-05 15:40 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-08-24 5:12 [PATCH v2] btrfs: slience the sparse warn of rcu_string Wang Yugui
2022-08-24 7:25 ` Anand Jain
2022-09-02 13:55 ` David Sterba
2022-09-05 3:57 ` Wang Yugui
2022-09-05 15:34 ` David Sterba
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