From: Colin Ian King <[email protected]>
An earlier fix to replace an IS_ERR check on lp with a null check
on lp didn't remove a following null check on lp. The second null
check is redundant and can be removed.
Addresses-Coverity: ("Logically dead code")
Fixes: c770cd5190ba ("ubifs: fix an IS_ERR() vs NULL check")
Signed-off-by: Colin Ian King <[email protected]>
---
fs/ubifs/gc.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index 7cc22d7317ea..465beea52176 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -899,8 +899,6 @@ int ubifs_gc_start_commit(struct ubifs_info *c)
err = -ENOMEM;
goto out;
}
- if (!lp)
- break;
idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);
if (!idx_gc) {
err = -ENOMEM;
--
2.31.1
?? 2021/6/21 23:22, Colin King д??:
> From: Colin Ian King <[email protected]>
>
> An earlier fix to replace an IS_ERR check on lp with a null check
> on lp didn't remove a following null check on lp. The second null
> check is redundant and can be removed.
>
> Addresses-Coverity: ("Logically dead code")
> Fixes: c770cd5190ba ("ubifs: fix an IS_ERR() vs NULL check")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> fs/ubifs/gc.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
> index 7cc22d7317ea..465beea52176 100644
> --- a/fs/ubifs/gc.c
> +++ b/fs/ubifs/gc.c
> @@ -899,8 +899,6 @@ int ubifs_gc_start_commit(struct ubifs_info *c)
> err = -ENOMEM;
> goto out;
> }
Hi Colin,
I just found out about it today thanks to your patch. Commit
c770cd5190ba ("ubifs: fix an IS_ERR() vs NULL check") did import a new
problem that ubifs_gc_start_commit() may return -ENOMEM while syncing fs.
I guess ubifs_fast_find_frdi_idx() return NULL pointer is the
termination condition in while-loop, which means we cannot get a
freeable index LEB in ubifs_gc_start_commit().
> - if (!lp)
> - break;
> idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);
> if (!idx_gc) {
> err = -ENOMEM;
>
BTW, the following modifications may be what you want?
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index 7cc22d7317ea..b1f276599b04 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -895,10 +895,6 @@ int ubifs_gc_start_commit(struct ubifs_info *c)
/* Record index freeable LEBs for unmapping after commit */
while (1) {
lp = ubifs_fast_find_frdi_idx(c);
- if (!lp) {
- err = -ENOMEM;
- goto out;
- }
if (!lp)
break;
idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb),
GFP_NOFS);
On Tue, Jun 22, 2021 at 10:38:52AM +0800, Zhihao Cheng wrote:
> 在 2021/6/21 23:22, Colin King 写道:
> > From: Colin Ian King <[email protected]>
> >
> > An earlier fix to replace an IS_ERR check on lp with a null check
> > on lp didn't remove a following null check on lp. The second null
> > check is redundant and can be removed.
> >
> > Addresses-Coverity: ("Logically dead code")
> > Fixes: c770cd5190ba ("ubifs: fix an IS_ERR() vs NULL check")
> > Signed-off-by: Colin Ian King <[email protected]>
> > ---
> > fs/ubifs/gc.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
> > index 7cc22d7317ea..465beea52176 100644
> > --- a/fs/ubifs/gc.c
> > +++ b/fs/ubifs/gc.c
> > @@ -899,8 +899,6 @@ int ubifs_gc_start_commit(struct ubifs_info *c)
> > err = -ENOMEM;
> > goto out;
> > }
> Hi Colin,
> I just found out about it today thanks to your patch. Commit c770cd5190ba
> ("ubifs: fix an IS_ERR() vs NULL check") did import a new problem that
> ubifs_gc_start_commit() may return -ENOMEM while syncing fs.
> I guess ubifs_fast_find_frdi_idx() return NULL pointer is the termination
> condition in while-loop, which means we cannot get a freeable index LEB in
> ubifs_gc_start_commit().
Ugh... I'm so sorry. My patch was clearly wrong. I've tried before to
add a Smatch check which warns about duplicative NULL checks, but I
think this gives me a new idea to try. Hopefully, it will prevent this
in the future.
Yeah, and it's my check which needs to be deleted, not the other one.
regards,
dan carpenter
----- Ursprüngliche Mail -----
> I just found out about it today thanks to your patch. Commit
> c770cd5190ba ("ubifs: fix an IS_ERR() vs NULL check") did import a new
> problem that ubifs_gc_start_commit() may return -ENOMEM while syncing fs.
> I guess ubifs_fast_find_frdi_idx() return NULL pointer is the
> termination condition in while-loop, which means we cannot get a
> freeable index LEB in ubifs_gc_start_commit().
Good catch! :-)
>> - if (!lp)
>> - break;
>> idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);
>> if (!idx_gc) {
>> err = -ENOMEM;
>>
> BTW, the following modifications may be what you want?
> diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
> index 7cc22d7317ea..b1f276599b04 100644
> --- a/fs/ubifs/gc.c
> +++ b/fs/ubifs/gc.c
> @@ -895,10 +895,6 @@ int ubifs_gc_start_commit(struct ubifs_info *c)
> /* Record index freeable LEBs for unmapping after commit */
> while (1) {
> lp = ubifs_fast_find_frdi_idx(c);
> - if (!lp) {
> - err = -ENOMEM;
> - goto out;
> - }
> if (!lp)
> break;
> idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb),
> GFP_NOFS);
I'll drop Dan's patch from -next. Do you want to send a followup patch which removes the
in vain check?
Thanks,
//richard
----- Ursprüngliche Mail -----
> Ugh... I'm so sorry. My patch was clearly wrong. I've tried before to
No need to worry. :)
> add a Smatch check which warns about duplicative NULL checks, but I
> think this gives me a new idea to try. Hopefully, it will prevent this
> in the future.
Sounds great!
Thanks,
//richard