From: ebiederm@xmission•com (Eric W. Biederman)
To: <linux-kernel@vger•kernel.org>
Cc: <linux-fsdevel@vger•kernel.org>, <netdev@vger•kernel.org>,
Lucian Adrian Grijincu <lucian.grijincu@gmail•com>,
Damien Millescamps <damien.millescamps@6wind•com>,
Dan Carpenter <dan.carpenter@oracle•com>
Subject: [PATCH 3/4] sysctl: Comments to make the code clearer.
Date: Wed, 01 Feb 2012 19:29:39 -0800 [thread overview]
Message-ID: <m1pqdxvroc.fsf_-_@fess.ebiederm.org> (raw)
In-Reply-To: <m139atx6bs.fsf@fess.ebiederm.org> (Eric W. Biederman's message of "Wed, 01 Feb 2012 19:27:51 -0800")
Document get_subdir and that find_subdir alwasy takes a reference.
Suggested-by: Lucian Adrian Grijincu <lucian.grijincu@gmail•com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission•com>
---
fs/proc/proc_sysctl.c | 16 ++++++++++++++++
1 files changed, 16 insertions(+), 0 deletions(-)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 722ec11..e5601dc 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -73,6 +73,7 @@ static int namecmp(const char *name1, int len1, const char *name2, int len2)
return cmp;
}
+/* Called under sysctl_lock */
static struct ctl_table *find_entry(struct ctl_table_header **phead,
struct ctl_dir *dir, const char *name, int namelen)
{
@@ -864,6 +865,18 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set,
return new;
}
+/**
+ * get_subdir - find or create a subdir with the specified name.
+ * @dir: Directory to create the subdirectory in
+ * @name: The name of the subdirectory to find or create
+ * @namelen: The length of name
+ *
+ * Takes a directory with an elevated reference count so we know that
+ * if we drop the lock the directory will not go away. Upon success
+ * the reference is moved from @dir to the returned subdirectory.
+ * Upon error an error code is returned and the reference on @dir is
+ * simply dropped.
+ */
static struct ctl_dir *get_subdir(struct ctl_dir *dir,
const char *name, int namelen)
{
@@ -885,12 +898,14 @@ static struct ctl_dir *get_subdir(struct ctl_dir *dir,
if (!new)
goto failed;
+ /* Was the subdir added while we dropped the lock? */
subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
goto failed;
+ /* Nope. Use the our freshly made directory entry. */
err = insert_header(dir, &new->header);
subdir = ERR_PTR(err);
if (err)
@@ -1190,6 +1205,7 @@ struct ctl_table_header *__register_sysctl_table(
spin_lock(&sysctl_lock);
dir = &set->dir;
+ /* Reference moved down the diretory tree get_subdir */
dir->header.nreg++;
spin_unlock(&sysctl_lock);
--
1.7.2.5
next prev parent reply other threads:[~2012-02-02 3:29 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-27 4:45 [Review][PATCH][0/29] sysctl rewrite for speed and clarity Eric W. Biederman
2012-01-27 4:49 ` [PATCH 01/29] sysctl: remove impossible condition check Eric W. Biederman
2012-01-27 4:49 ` [PATCH 02/29] sysctl: Consolidate !CONFIG_SYSCTL handling Eric W. Biederman
2012-01-27 4:49 ` [PATCH 03/29] sysctl: Register the base sysctl table like any other sysctl table Eric W. Biederman
2012-01-27 4:49 ` [PATCH 04/29] sysctl: Move the implementation into fs/proc/proc_sysctl.c Eric W. Biederman
2012-01-27 4:49 ` [PATCH 05/29] sysctl: Make the directories have nlink == 1 Eric W. Biederman
2012-01-27 4:49 ` [PATCH 06/29] sysctl: Implement retire_sysctl_set Eric W. Biederman
2012-01-27 4:49 ` [PATCH 07/29] sysctl: Remove the unnecessary sysctl_set parent concept Eric W. Biederman
2012-01-27 4:49 ` [PATCH 08/29] sysctl: Create local copies of directory names used in paths Eric W. Biederman
2012-01-27 4:49 ` [PATCH 09/29] sysctl: Add support for register sysctl tables with a normal cstring path Eric W. Biederman
2012-01-27 4:49 ` [PATCH 10/29] sysctl: Add ctl_table chains into cstring paths Eric W. Biederman
2012-01-27 4:49 ` [PATCH 11/29] sysctl: register only tables of sysctl files Eric W. Biederman
2012-01-27 4:49 ` [PATCH 12/29] sysctl: Improve the sysctl sanity checks Eric W. Biederman
2012-01-27 4:49 ` [PATCH 13/29] sysctl: Remove the now unused ctl_table parent field Eric W. Biederman
2012-01-27 4:49 ` [PATCH 14/29] sysctl: A more obvious version of grab_header Eric W. Biederman
2012-01-27 4:49 ` [PATCH 15/29] sysctl: Initial support for auto-unregistering sysctl tables Eric W. Biederman
2012-01-27 4:49 ` [PATCH 16/29] sysctl: Factor out init_header from __register_sysctl_paths Eric W. Biederman
2012-01-27 4:49 ` [PATCH 17/29] sysctl: Factor out insert_header and erase_header Eric W. Biederman
2012-01-27 4:49 ` [PATCH 18/29] sysctl: Normalize the root_table data structure Eric W. Biederman
2012-01-27 4:50 ` [PATCH 19/29] sysctl: Rewrite proc_sys_lookup introducing find_entry and lookup_entry Eric W. Biederman
2012-01-27 4:50 ` [PATCH 20/29] sysctl: Rewrite proc_sys_readdir in terms of first_entry and next_entry Eric W. Biederman
2012-01-27 4:50 ` [PATCH 21/29] sysctl: Add a root pointer to ctl_table_set Eric W. Biederman
2012-01-27 4:50 ` [PATCH 22/29] sysctl: Stop requiring explicit management of sysctl directories Eric W. Biederman
2012-01-27 4:50 ` [PATCH 23/29] sysctl: Add sysctl_print_dir and use it in get_subdir Eric W. Biederman
2012-01-27 4:50 ` [PATCH 24/29] sysctl: Replace root_list with links between sysctl_table_sets Eric W. Biederman
2012-01-27 4:50 ` [PATCH 25/29] sysctl: Modify __register_sysctl_paths to take a set instead of a root and an nsproxy Eric W. Biederman
2012-01-27 4:50 ` [PATCH 26/29] sysctl: Move sysctl_check_dups into insert_header Eric W. Biederman
2012-01-27 4:50 ` [PATCH 27/29] sysctl: Make the header lists per directory Eric W. Biederman
2012-01-27 4:50 ` [PATCH 28/29] sysctl: Index sysctl directories with rbtrees Eric W. Biederman
2012-01-27 4:50 ` [PATCH 29/29] sysctl: Add register_sysctl for normal sysctl users Eric W. Biederman
2012-01-27 4:51 ` [PATCH 01/29] sysctl: remove impossible condition check Eric W. Biederman
2012-01-27 4:51 ` [PATCH 02/29] sysctl: Consolidate !CONFIG_SYSCTL handling Eric W. Biederman
2012-01-27 4:51 ` [PATCH 03/29] sysctl: Register the base sysctl table like any other sysctl table Eric W. Biederman
2012-01-27 4:51 ` [PATCH 04/29] sysctl: Move the implementation into fs/proc/proc_sysctl.c Eric W. Biederman
2012-01-27 4:51 ` [PATCH 05/29] sysctl: Make the directories have nlink == 1 Eric W. Biederman
2012-01-27 4:51 ` [PATCH 06/29] sysctl: Implement retire_sysctl_set Eric W. Biederman
2012-01-27 4:51 ` [PATCH 07/29] sysctl: Remove the unnecessary sysctl_set parent concept Eric W. Biederman
2012-01-27 4:51 ` [PATCH 08/29] sysctl: Create local copies of directory names used in paths Eric W. Biederman
2012-01-27 4:51 ` [PATCH 09/29] sysctl: Add support for register sysctl tables with a normal cstring path Eric W. Biederman
2012-01-27 4:51 ` [PATCH 10/29] sysctl: Add ctl_table chains into cstring paths Eric W. Biederman
2012-01-27 4:51 ` [PATCH 11/29] sysctl: register only tables of sysctl files Eric W. Biederman
2012-01-27 4:51 ` [PATCH 12/29] sysctl: Improve the sysctl sanity checks Eric W. Biederman
2012-01-27 4:51 ` [PATCH 13/29] sysctl: Remove the now unused ctl_table parent field Eric W. Biederman
2012-01-27 4:51 ` [PATCH 14/29] sysctl: A more obvious version of grab_header Eric W. Biederman
2012-01-27 4:51 ` [PATCH 15/29] sysctl: Initial support for auto-unregistering sysctl tables Eric W. Biederman
2012-01-27 4:51 ` [PATCH 16/29] sysctl: Factor out init_header from __register_sysctl_paths Eric W. Biederman
2012-01-27 4:51 ` [PATCH 17/29] sysctl: Factor out insert_header and erase_header Eric W. Biederman
2012-01-27 4:51 ` [PATCH 18/29] sysctl: Normalize the root_table data structure Eric W. Biederman
2012-01-29 17:36 ` Lucian Adrian Grijincu
2012-01-30 0:22 ` Eric W. Biederman
2012-01-27 4:51 ` [PATCH 19/29] sysctl: Rewrite proc_sys_lookup introducing find_entry and lookup_entry Eric W. Biederman
2012-01-29 15:49 ` Lucian Adrian Grijincu
2012-01-27 4:51 ` [PATCH 20/29] sysctl: Rewrite proc_sys_readdir in terms of first_entry and next_entry Eric W. Biederman
2012-01-27 4:51 ` [PATCH 21/29] sysctl: Add a root pointer to ctl_table_set Eric W. Biederman
2012-01-29 17:19 ` Lucian Adrian Grijincu
2012-01-27 4:51 ` [PATCH 22/29] sysctl: Stop requiring explicit management of sysctl directories Eric W. Biederman
2012-01-29 19:31 ` Lucian Adrian Grijincu
2012-01-31 4:45 ` Eric W. Biederman
2012-01-27 4:51 ` [PATCH 23/29] sysctl: Add sysctl_print_dir and use it in get_subdir Eric W. Biederman
2012-01-27 4:52 ` [PATCH 24/29] sysctl: Replace root_list with links between sysctl_table_sets Eric W. Biederman
2012-01-30 0:01 ` Lucian Adrian Grijincu
2012-01-31 3:10 ` Eric W. Biederman
2012-01-30 17:51 ` Dave Jones
2012-01-31 2:11 ` Eric W. Biederman
2012-01-31 2:13 ` Joe Perches
2012-01-27 4:52 ` [PATCH 25/29] sysctl: Modify __register_sysctl_paths to take a set instead of a root and an nsproxy Eric W. Biederman
2012-01-27 4:52 ` [PATCH 26/29] sysctl: Move sysctl_check_dups into insert_header Eric W. Biederman
2012-01-27 4:52 ` [PATCH 27/29] sysctl: Make the header lists per directory Eric W. Biederman
2012-01-27 4:52 ` [PATCH 28/29] sysctl: Index sysctl directories with rbtrees Eric W. Biederman
2012-01-27 4:52 ` [PATCH 29/29] sysctl: Add register_sysctl for normal sysctl users Eric W. Biederman
2012-02-02 3:27 ` [Review][PATCH][0/4] sysctl bitty fixes Eric W. Biederman
2012-02-02 3:28 ` [PATCH 1/4] sysctl: An easier to read version of find_subdir Eric W. Biederman
2012-02-02 3:29 ` [PATCH 2/4] sysctl: Correct error return from get_subdir Eric W. Biederman
2012-02-02 3:29 ` Eric W. Biederman [this message]
2012-02-02 16:28 ` [PATCH 3/4] sysctl: Comments to make the code clearer Ben Hutchings
2012-02-02 3:30 ` [PATCH 4/4] sysctl: Don't call sysctl_follow_link unless we are a link Eric W. Biederman
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