linux-kernel - [PATCH 2/4] x86/alternatives: Don't need text_mutex when text

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Date:   Sat, 28 Oct 2017 20:50:55 +0800
From:   Zhou Chengming <zhouchengming1@...wei.com>
To:     <mhiramat@...nel.org>, <bp@...e.de>, <peterz@...radead.org>,
        <ananth@...ux.vnet.ibm.com>, <anil.s.keshavamurthy@...el.com>,
        <davem@...emloft.net>, <tglx@...utronix.de>, <jkosina@...e.cz>,
        <rostedt@...dmis.org>, <mjurczyk@...gle.com>
CC:     <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <zhouchengming1@...wei.com>
Subject: [PATCH 2/4] x86/alternatives: Don't need text_mutex when text_poke() on UP

The alternatives_smp_lock/unlock only be used on UP, so we don't
need to hold the text_mutex when text_poke(). Then in the next patch,
we can remove the outside smp_alt mutex too.

Signed-off-by: Zhou Chengming <zhouchengming1@...wei.com>
---
 arch/x86/kernel/alternative.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 8549269..5c3f593 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -442,7 +442,6 @@ static void alternatives_smp_lock(const s32 *start, const s32 *end,
 {
 	const s32 *poff;
 
-	mutex_lock(&text_mutex);
 	for (poff = start; poff < end; poff++) {
 		u8 *ptr = (u8 *)poff + *poff;
 
@@ -452,7 +451,6 @@ static void alternatives_smp_lock(const s32 *start, const s32 *end,
 		if (*ptr == 0x3e)
 			text_poke(ptr, ((unsigned char []){0xf0}), 1);
 	}
-	mutex_unlock(&text_mutex);
 }
 
 static void alternatives_smp_unlock(const s32 *start, const s32 *end,
@@ -460,7 +458,6 @@ static void alternatives_smp_unlock(const s32 *start, const s32 *end,
 {
 	const s32 *poff;
 
-	mutex_lock(&text_mutex);
 	for (poff = start; poff < end; poff++) {
 		u8 *ptr = (u8 *)poff + *poff;
 
@@ -470,7 +467,6 @@ static void alternatives_smp_unlock(const s32 *start, const s32 *end,
 		if (*ptr == 0xf0)
 			text_poke(ptr, ((unsigned char []){0x3E}), 1);
 	}
-	mutex_unlock(&text_mutex);
 }
 
 struct smp_alt_module {
-- 
1.8.3.1