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Message-ID: <20071116151015.GE19517@localhost.sw.ru>
Date: Fri, 16 Nov 2007 18:10:15 +0300
From: Alexey Dobriyan <adobriyan@...ru>
To: akpm@...l.org
Cc: linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
devel@...nvz.org
Subject: [PATCH 3/4] proc: simplify remove_proc_entry() wrt locking
We can take proc_subdir_lock for duration of list searching and removing
from lists only. It can't hurt -- we can gather any amount of looked up
PDEs right after proc_subdir_lock droppage in proc_lookup() anyway.
Current code should already deal with this correctly.
Also this should make code more undestandable:
* original looks like a loop, however, it's a loop with unconditional
trailing "break;" -- not loop at all.
* more explicit statement that proc_subdir_lock protects only ->subdir lists.
Signed-off-by: Alexey Dobriyan <adobriyan@...ru>
---
fs/proc/generic.c | 67 +++++++++++++++++++++++++-----------------------------
1 file changed, 32 insertions(+), 35 deletions(-)
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -686,12 +686,12 @@ void free_proc_entry(struct proc_dir_entry *de)
void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
{
struct proc_dir_entry **p;
- struct proc_dir_entry *de;
+ struct proc_dir_entry *de = NULL;
const char *fn = name;
int len;
if (!parent && xlate_proc_name(name, &parent, &fn) != 0)
- goto out;
+ return;
len = strlen(fn);
spin_lock(&proc_subdir_lock);
@@ -701,45 +701,42 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
de = *p;
*p = de->next;
de->next = NULL;
+ }
+ spin_unlock(&proc_subdir_lock);
+ if (!de)
+ return;
- spin_lock(&de->pde_unload_lock);
- /*
- * Stop accepting new callers into module. If you're
- * dynamically allocating ->proc_fops, save a pointer somewhere.
- */
- de->proc_fops = NULL;
- /* Wait until all existing callers into module are done. */
- if (de->pde_users > 0) {
- DECLARE_COMPLETION_ONSTACK(c);
+ spin_lock(&de->pde_unload_lock);
+ /*
+ * Stop accepting new callers into module. If you're
+ * dynamically allocating ->proc_fops, save a pointer somewhere.
+ */
+ de->proc_fops = NULL;
+ /* Wait until all existing callers into module are done. */
+ if (de->pde_users > 0) {
+ DECLARE_COMPLETION_ONSTACK(c);
- if (!de->pde_unload_completion)
- de->pde_unload_completion = &c;
+ if (!de->pde_unload_completion)
+ de->pde_unload_completion = &c;
- spin_unlock(&de->pde_unload_lock);
- spin_unlock(&proc_subdir_lock);
+ spin_unlock(&de->pde_unload_lock);
- wait_for_completion(de->pde_unload_completion);
+ wait_for_completion(de->pde_unload_completion);
- spin_lock(&proc_subdir_lock);
- goto continue_removing;
- }
- spin_unlock(&de->pde_unload_lock);
+ goto continue_removing;
+ }
+ spin_unlock(&de->pde_unload_lock);
continue_removing:
- if (S_ISDIR(de->mode))
- parent->nlink--;
- de->nlink = 0;
- WARN_ON(de->subdir);
- if (!atomic_read(&de->count))
- free_proc_entry(de);
- else {
- de->deleted = 1;
- printk("remove_proc_entry: %s/%s busy, count=%d\n",
- parent->name, de->name, atomic_read(&de->count));
- }
- break;
+ if (S_ISDIR(de->mode))
+ parent->nlink--;
+ de->nlink = 0;
+ WARN_ON(de->subdir);
+ if (!atomic_read(&de->count))
+ free_proc_entry(de);
+ else {
+ de->deleted = 1;
+ printk("remove_proc_entry: %s/%s busy, count=%d\n",
+ parent->name, de->name, atomic_read(&de->count));
}
- spin_unlock(&proc_subdir_lock);
-out:
- return;
}
-
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