linux-kernel - [PATCH 3/8] sysctl: Remove check for sentinel element in ctl

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Date: Tue, 04 Jun 2024 08:29:21 +0200
From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
 Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>, 
 Boqun Feng <boqun.feng@...il.com>, Suren Baghdasaryan <surenb@...gle.com>, 
 Kent Overstreet <kent.overstreet@...ux.dev>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 Luis Chamberlain <mcgrof@...nel.org>, Kees Cook <keescook@...omium.org>, 
 Joel Granados <j.granados@...sung.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
 linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 3/8] sysctl: Remove check for sentinel element in ctl_table
 arrays

From: Joel Granados <j.granados@...sung.com>

Use ARRAY_SIZE exclusively by removing the check to ->procname in the
stopping criteria of the loops traversing ctl_table arrays. This commit
finalizes the removal of the sentinel elements at the end of ctl_table
arrays which reduces the build time size and run time memory bloat by
~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove the entry->procname evaluation from the for loop stopping
criteria in sysctl and sysctl_net.

Signed-off-by: Joel Granados <j.granados@...sung.com>
---
 fs/proc/proc_sysctl.c |  2 +-
 net/sysctl_net.c      | 11 ++---------
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index b1c2c0b82116..d4ba7ad9dbe0 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -21,7 +21,7 @@

 #define list_for_each_table_entry(entry, header)	\
 	entry = header->ctl_table;			\
-	for (size_t i = 0 ; i < header->ctl_table_size && entry->procname; ++i, entry++)
+	for (size_t i = 0 ; i < header->ctl_table_size; ++i, entry++)

 static const struct dentry_operations proc_sys_dentry_operations;
 static const struct file_operations proc_sys_file_operations;
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index f5017012a049..19e8048241ba 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -127,7 +127,7 @@ static void ensure_safe_net_sysctl(struct net *net, const char *path,

 	pr_debug("Registering net sysctl (net %p): %s\n", net, path);
 	ent = table;
-	for (size_t i = 0; i < table_size && ent->procname; ent++, i++) {
+	for (size_t i = 0; i < table_size; ent++, i++) {
 		unsigned long addr;
 		const char *where;

@@ -165,17 +165,10 @@ struct ctl_table_header *register_net_sysctl_sz(struct net *net,
 						struct ctl_table *table,
 						size_t table_size)
 {
-	int count;
-	struct ctl_table *entry;
-
 	if (!net_eq(net, &init_net))
 		ensure_safe_net_sysctl(net, path, table, table_size);

-	entry = table;
-	for (count = 0 ; count < table_size && entry->procname; entry++, count++)
-		;
-
-	return __register_sysctl_table(&net->sysctls, path, table, count);
+	return __register_sysctl_table(&net->sysctls, path, table, table_size);
 }
 EXPORT_SYMBOL_GPL(register_net_sysctl_sz);

-- 
2.43.0