* [PATCH 0/3] Trivial code clean for procfs
@ 2012-09-03 14:14 yan
2012-09-03 14:14 ` [PATCH 1/3] proc: return -ENOMEM when inode allocation failed yan
` (2 more replies)
0 siblings, 3 replies; 13+ messages in thread
From: yan @ 2012-09-03 14:14 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel
yan (3):
proc: return -ENOMEM when inode allocation failed
proc: no need to initialize proc_inode->fd in proc_get_inode
proc: use kzalloc instead of kmalloc and memset
fs/proc/generic.c | 5 ++---
fs/proc/inode.c | 1 -
2 files changed, 2 insertions(+), 4 deletions(-)
--
1.7.9.5
^ permalink raw reply [flat|nested] 13+ messages in thread* [PATCH 1/3] proc: return -ENOMEM when inode allocation failed 2012-09-03 14:14 [PATCH 0/3] Trivial code clean for procfs yan @ 2012-09-03 14:14 ` yan 2012-09-04 0:38 ` Ryan Mallon 2012-09-04 3:02 ` Cong Wang 2012-09-03 14:14 ` [PATCH 2/3] proc : no need to initialize proc_inode->fd in proc_get_inode yan 2012-09-03 14:14 ` [PATCH 3/3] proc: use kzalloc instead of kmalloc and memset yan 2 siblings, 2 replies; 13+ messages in thread From: yan @ 2012-09-03 14:14 UTC (permalink / raw) To: akpm; +Cc: linux-kernel Signed-off-by: yan <clouds.yan@gmail.com> --- fs/proc/generic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index b3647fe..9e8f631 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -427,7 +427,7 @@ struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir, if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { pde_get(de); spin_unlock(&proc_subdir_lock); - error = -EINVAL; + error = -ENOMEM; inode = proc_get_inode(dir->i_sb, de); goto out_unlock; } -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 1/3] proc: return -ENOMEM when inode allocation failed 2012-09-03 14:14 ` [PATCH 1/3] proc: return -ENOMEM when inode allocation failed yan @ 2012-09-04 0:38 ` Ryan Mallon 2012-09-04 3:02 ` Cong Wang 1 sibling, 0 replies; 13+ messages in thread From: Ryan Mallon @ 2012-09-04 0:38 UTC (permalink / raw) To: yan; +Cc: akpm, linux-kernel On 04/09/12 00:14, yan wrote: > Signed-off-by: yan <clouds.yan@gmail.com> > --- > fs/proc/generic.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c > index b3647fe..9e8f631 100644 > --- a/fs/proc/generic.c > +++ b/fs/proc/generic.c > @@ -427,7 +427,7 @@ struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir, > if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { > pde_get(de); > spin_unlock(&proc_subdir_lock); > - error = -EINVAL; > + error = -ENOMEM; This seems incorrect. This function doesn't allocate anything, it looks up an inode. From my reading it looks like -EINVAL is returned here if the dentry name matches, but the inode cannot be found. ~Ryan ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/3] proc: return -ENOMEM when inode allocation failed 2012-09-03 14:14 ` [PATCH 1/3] proc: return -ENOMEM when inode allocation failed yan 2012-09-04 0:38 ` Ryan Mallon @ 2012-09-04 3:02 ` Cong Wang 2012-09-04 9:22 ` yan yan 1 sibling, 1 reply; 13+ messages in thread From: Cong Wang @ 2012-09-04 3:02 UTC (permalink / raw) To: yan; +Cc: akpm, linux-kernel On 09/03/2012 10:14 PM, yan wrote: > Signed-off-by: yan <clouds.yan@gmail.com> Please provide a changelog to explain why we need this patch. > --- > fs/proc/generic.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c > index b3647fe..9e8f631 100644 > --- a/fs/proc/generic.c > +++ b/fs/proc/generic.c > @@ -427,7 +427,7 @@ struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir, > if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { > pde_get(de); > spin_unlock(&proc_subdir_lock); > - error = -EINVAL; > + error = -ENOMEM; Why the !memcmp() case is related with ENOMEM ?? ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/3] proc: return -ENOMEM when inode allocation failed 2012-09-04 3:02 ` Cong Wang @ 2012-09-04 9:22 ` yan yan 2012-09-04 22:41 ` Andrew Morton 2012-09-05 7:15 ` Cong Wang 0 siblings, 2 replies; 13+ messages in thread From: yan yan @ 2012-09-04 9:22 UTC (permalink / raw) To: Cong Wang; +Cc: akpm, linux-kernel 2012/9/4 Cong Wang <xiyou.wangcong@gmail.com>: > On 09/03/2012 10:14 PM, yan wrote: >> >> Signed-off-by: yan <clouds.yan@gmail.com> > > > Please provide a changelog to explain why we need this patch. I think the title is self explained. >> --- >> fs/proc/generic.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/proc/generic.c b/fs/proc/generic.c >> index b3647fe..9e8f631 100644 >> --- a/fs/proc/generic.c >> +++ b/fs/proc/generic.c >> @@ -427,7 +427,7 @@ struct dentry *proc_lookup_de(struct proc_dir_entry >> *de, struct inode *dir, >> if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { >> pde_get(de); >> spin_unlock(&proc_subdir_lock); >> - error = -EINVAL; >> + error = -ENOMEM; > > > Why the !memcmp() case is related with ENOMEM ?? We are presetting 'error' here. The following proc_get_inode() will try to get an inode, either from inode cache or allocate a new one (and fill it). If we get a NULL inode, that means allocation failed. That's how ENOMEM involved. Thank you for your reply. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/3] proc: return -ENOMEM when inode allocation failed 2012-09-04 9:22 ` yan yan @ 2012-09-04 22:41 ` Andrew Morton 2012-09-05 7:15 ` Cong Wang 1 sibling, 0 replies; 13+ messages in thread From: Andrew Morton @ 2012-09-04 22:41 UTC (permalink / raw) To: yan yan; +Cc: Cong Wang, linux-kernel On Tue, 4 Sep 2012 17:22:15 +0800 yan yan <clouds.yan@gmail.com> wrote: > 2012/9/4 Cong Wang <xiyou.wangcong@gmail.com>: > > On 09/03/2012 10:14 PM, yan wrote: > >> > >> Signed-off-by: yan <clouds.yan@gmail.com> > > > > > > Please provide a changelog to explain why we need this patch. > > I think the title is self explained. Given this review feedback, the title alone was obviously insufficient! I provided the following changelog text: : If proc_get_inode() returns NULL then presumably it encountered memory : exhaustion. proc_lookup_de() should return -ENOMEM in this case, not : -EINVAL. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 1/3] proc: return -ENOMEM when inode allocation failed 2012-09-04 9:22 ` yan yan 2012-09-04 22:41 ` Andrew Morton @ 2012-09-05 7:15 ` Cong Wang 2012-09-05 7:57 ` yan yan 1 sibling, 1 reply; 13+ messages in thread From: Cong Wang @ 2012-09-05 7:15 UTC (permalink / raw) To: yan yan; +Cc: akpm, linux-kernel On 09/04/2012 05:22 PM, yan yan wrote: > 2012/9/4 Cong Wang <xiyou.wangcong@gmail.com>: >> On 09/03/2012 10:14 PM, yan wrote: >>> >>> Signed-off-by: yan <clouds.yan@gmail.com> >> >> >> Please provide a changelog to explain why we need this patch. > > I think the title is self explained. > > >>> --- >>> fs/proc/generic.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/proc/generic.c b/fs/proc/generic.c >>> index b3647fe..9e8f631 100644 >>> --- a/fs/proc/generic.c >>> +++ b/fs/proc/generic.c >>> @@ -427,7 +427,7 @@ struct dentry *proc_lookup_de(struct proc_dir_entry >>> *de, struct inode *dir, >>> if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { >>> pde_get(de); >>> spin_unlock(&proc_subdir_lock); >>> - error = -EINVAL; >>> + error = -ENOMEM; >> >> >> Why the !memcmp() case is related with ENOMEM ?? > > We are presetting 'error' here. The following proc_get_inode() will try > to get an inode, either from inode cache or allocate a new one (and fill it). > > If we get a NULL inode, that means allocation failed. That's how > ENOMEM involved. Then the following patch is probably better than yours: diff --git a/fs/proc/generic.c b/fs/proc/generic.c index b3647fe..6b22913 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -427,12 +427,16 @@ struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir, if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { pde_get(de); spin_unlock(&proc_subdir_lock); - error = -EINVAL; inode = proc_get_inode(dir->i_sb, de); + if (!inode) { + error = -ENOMEM; + goto out_put; + } goto out_unlock; } } spin_unlock(&proc_subdir_lock); + out_unlock: if (inode) { @@ -440,6 +444,8 @@ out_unlock: d_add(dentry, inode); return NULL; } +out_put: + if (de) pde_put(de); return ERR_PTR(error); ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 1/3] proc: return -ENOMEM when inode allocation failed 2012-09-05 7:15 ` Cong Wang @ 2012-09-05 7:57 ` yan yan 0 siblings, 0 replies; 13+ messages in thread From: yan yan @ 2012-09-05 7:57 UTC (permalink / raw) To: Cong Wang; +Cc: akpm, linux-kernel 2012/9/5 Cong Wang <xiyou.wangcong@gmail.com>: >>> Why the !memcmp() case is related with ENOMEM ?? >> >> >> We are presetting 'error' here. The following proc_get_inode() will try >> to get an inode, either from inode cache or allocate a new one (and fill >> it). >> >> If we get a NULL inode, that means allocation failed. That's how >> ENOMEM involved. > > > Then the following patch is probably better than yours: > > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c > index b3647fe..6b22913 100644 > --- a/fs/proc/generic.c > +++ b/fs/proc/generic.c > @@ -427,12 +427,16 @@ struct dentry *proc_lookup_de(struct proc_dir_entry > *de, struct inode *dir, > > if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { > pde_get(de); > spin_unlock(&proc_subdir_lock); > - error = -EINVAL; > inode = proc_get_inode(dir->i_sb, de); > + if (!inode) { > + error = -ENOMEM; > + goto out_put; > + } > goto out_unlock; > } > } > spin_unlock(&proc_subdir_lock); > + > out_unlock: > > if (inode) { > @@ -440,6 +444,8 @@ out_unlock: > d_add(dentry, inode); > return NULL; > } > +out_put: > + > if (de) > pde_put(de); > return ERR_PTR(error); > > Change so many lines to save a assignment to 'error' ... That's a stye issue. I prefer a simple change, though your change seems OK to me. Thanks ^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH 2/3] proc : no need to initialize proc_inode->fd in proc_get_inode 2012-09-03 14:14 [PATCH 0/3] Trivial code clean for procfs yan 2012-09-03 14:14 ` [PATCH 1/3] proc: return -ENOMEM when inode allocation failed yan @ 2012-09-03 14:14 ` yan 2012-09-04 22:49 ` Andrew Morton 2012-09-03 14:14 ` [PATCH 3/3] proc: use kzalloc instead of kmalloc and memset yan 2 siblings, 1 reply; 13+ messages in thread From: yan @ 2012-09-03 14:14 UTC (permalink / raw) To: akpm; +Cc: linux-kernel It has been initialized in proc_alloc_inode. Signed-off-by: yan <clouds.yan@gmail.com> --- fs/proc/inode.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 7ac817b..3b22bbd 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -450,7 +450,6 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) return NULL; if (inode->i_state & I_NEW) { inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; - PROC_I(inode)->fd = 0; PROC_I(inode)->pde = de; if (de->mode) { -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 2/3] proc : no need to initialize proc_inode->fd in proc_get_inode 2012-09-03 14:14 ` [PATCH 2/3] proc : no need to initialize proc_inode->fd in proc_get_inode yan @ 2012-09-04 22:49 ` Andrew Morton 0 siblings, 0 replies; 13+ messages in thread From: Andrew Morton @ 2012-09-04 22:49 UTC (permalink / raw) To: yan; +Cc: linux-kernel On Mon, 3 Sep 2012 22:14:06 +0800 yan <clouds.yan@gmail.com> wrote: > It has been initialized in proc_alloc_inode. > > ... I think what you mean here is that the preceding call to iget_locked() will call alloc_inode() which will call proc_alloc_inode() which clears pro_inode.fd. And if iget_locked() instead found the inode via find_inode_fast(), that inode will not have I_NEW set so this change has no effect. Yes? Please do spell things out in this level of detail so that others can check your logic. > --- a/fs/proc/inode.c > +++ b/fs/proc/inode.c > @@ -450,7 +450,6 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) > return NULL; > if (inode->i_state & I_NEW) { > inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; > - PROC_I(inode)->fd = 0; > PROC_I(inode)->pde = de; > > if (de->mode) { I provided this changelog: : proc_get_inode() obtains the inode via a call to iget_locked(). : iget_locked() calls alloc_inode() which will call proc_alloc_inode() which : clears proc_inode.fd, so there is no need to clear this field in : proc_get_inode(). : : If iget_locked() instead found the inode via find_inode_fast(), that inode : will not have I_NEW set so this change has no effect. ^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH 3/3] proc: use kzalloc instead of kmalloc and memset 2012-09-03 14:14 [PATCH 0/3] Trivial code clean for procfs yan 2012-09-03 14:14 ` [PATCH 1/3] proc: return -ENOMEM when inode allocation failed yan 2012-09-03 14:14 ` [PATCH 2/3] proc : no need to initialize proc_inode->fd in proc_get_inode yan @ 2012-09-03 14:14 ` yan 2012-09-04 0:44 ` Ryan Mallon 2 siblings, 1 reply; 13+ messages in thread From: yan @ 2012-09-03 14:14 UTC (permalink / raw) To: akpm; +Cc: linux-kernel Signed-off-by: yan <clouds.yan@gmail.com> --- fs/proc/generic.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 9e8f631..38de015 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -616,10 +616,9 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, len = strlen(fn); - ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL); + ent = kzalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL); if (!ent) goto out; - memset(ent, 0, sizeof(struct proc_dir_entry)); memcpy(ent->name, fn, len + 1); ent->namelen = len; ent->mode = mode; -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH 3/3] proc: use kzalloc instead of kmalloc and memset 2012-09-03 14:14 ` [PATCH 3/3] proc: use kzalloc instead of kmalloc and memset yan @ 2012-09-04 0:44 ` Ryan Mallon 2012-09-04 9:10 ` yan yan 0 siblings, 1 reply; 13+ messages in thread From: Ryan Mallon @ 2012-09-04 0:44 UTC (permalink / raw) To: yan; +Cc: akpm, linux-kernel On 04/09/12 00:14, yan wrote: > Signed-off-by: yan <clouds.yan@gmail.com> > --- > fs/proc/generic.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c > index 9e8f631..38de015 100644 > --- a/fs/proc/generic.c > +++ b/fs/proc/generic.c > @@ -616,10 +616,9 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, > > len = strlen(fn); > > - ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL); > + ent = kzalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL); > if (!ent) goto out; > > - memset(ent, 0, sizeof(struct proc_dir_entry)); > memcpy(ent->name, fn, len + 1); > ent->namelen = len; > ent->mode = mode; Note that this change results in slightly different behaviour. Before your change only sizeof(struct proc_dir_entry) is zero'ed by memset, and then the name is filled in (the len + 1 part). After your change the structure and the name field are both zeroed, so the name field is being written to twice. The cost is probably negligible though. ~Ryan ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH 3/3] proc: use kzalloc instead of kmalloc and memset 2012-09-04 0:44 ` Ryan Mallon @ 2012-09-04 9:10 ` yan yan 0 siblings, 0 replies; 13+ messages in thread From: yan yan @ 2012-09-04 9:10 UTC (permalink / raw) To: Ryan Mallon; +Cc: akpm, linux-kernel 2012/9/4 Ryan Mallon <rmallon@gmail.com> > > On 04/09/12 00:14, yan wrote: > > Signed-off-by: yan <clouds.yan@gmail.com> > > --- > > fs/proc/generic.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/fs/proc/generic.c b/fs/proc/generic.c > > index 9e8f631..38de015 100644 > > --- a/fs/proc/generic.c > > +++ b/fs/proc/generic.c > > @@ -616,10 +616,9 @@ static struct proc_dir_entry *__proc_create(struct > > proc_dir_entry **parent, > > > > len = strlen(fn); > > > > - ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, > > GFP_KERNEL); > > + ent = kzalloc(sizeof(struct proc_dir_entry) + len + 1, > > GFP_KERNEL); > > if (!ent) goto out; > > > > - memset(ent, 0, sizeof(struct proc_dir_entry)); > > memcpy(ent->name, fn, len + 1); > > ent->namelen = len; > > ent->mode = mode; > > Note that this change results in slightly different behaviour. Before > your change only sizeof(struct proc_dir_entry) is zero'ed by memset, and > then the name is filled in (the len + 1 part). After your change the > structure and the name field are both zeroed, so the name field is being > written to twice. The cost is probably negligible though. Oh, I didn't notice that actually. Thank you. ^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2012-09-05 7:57 UTC | newest] Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-09-03 14:14 [PATCH 0/3] Trivial code clean for procfs yan 2012-09-03 14:14 ` [PATCH 1/3] proc: return -ENOMEM when inode allocation failed yan 2012-09-04 0:38 ` Ryan Mallon 2012-09-04 3:02 ` Cong Wang 2012-09-04 9:22 ` yan yan 2012-09-04 22:41 ` Andrew Morton 2012-09-05 7:15 ` Cong Wang 2012-09-05 7:57 ` yan yan 2012-09-03 14:14 ` [PATCH 2/3] proc : no need to initialize proc_inode->fd in proc_get_inode yan 2012-09-04 22:49 ` Andrew Morton 2012-09-03 14:14 ` [PATCH 3/3] proc: use kzalloc instead of kmalloc and memset yan 2012-09-04 0:44 ` Ryan Mallon 2012-09-04 9:10 ` yan yan
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