linux-kernel - [PATCH] lib/crc32test: remove extra local_irq

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Message-ID: <patch.git-4369da00c06e.your-ad-here.call-01602859837-ext-1679@work.hours>
Date:   Fri, 16 Oct 2020 16:50:58 +0200
From:   Vasily Gorbik <gor@...ux.ibm.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] lib/crc32test: remove extra local_irq_disable/enable

Commit 4d004099a668 ("lockdep: Fix lockdep recursion") uncovered the
following issue in lib/crc32test reported on s390:

BUG: using __this_cpu_read() in preemptible [00000000] code: swapper/0/1
caller is lockdep_hardirqs_on_prepare+0x48/0x270
CPU: 6 PID: 1 Comm: swapper/0 Not tainted 5.9.0-next-20201015-15164-g03d992bd2de6 #19
Hardware name: IBM 3906 M04 704 (LPAR)
Call Trace:
 [<0000000000d54870>] show_stack+0x90/0xf8
 [<0000000000d675d2>] dump_stack+0xa2/0xd8
 [<0000000000d6c9ac>] check_preemption_disabled+0xe4/0xe8
 [<00000000001d6098>] lockdep_hardirqs_on_prepare+0x48/0x270
 [<00000000002ac274>] trace_hardirqs_on+0x9c/0x1b8
 [<0000000001441430>] crc32_test.isra.0+0x170/0x1c0
 [<0000000001441764>] crc32test_init+0x1c/0x40
 [<0000000000100cd0>] do_one_initcall+0x40/0x130
 [<0000000001411586>] do_initcalls+0x126/0x150
 [<0000000001411826>] kernel_init_freeable+0x1f6/0x230
 [<0000000000d6cc92>] kernel_init+0x22/0x150
 [<0000000000d7bcc4>] ret_from_fork+0x24/0x2c
no locks held by swapper/0/1.

Remove extra local_irq_disable/local_irq_enable helpers calls.

Fixes: 5fb7f87408f1 ("lib: add module support to crc32 tests")
Signed-off-by: Vasily Gorbik <gor@...ux.ibm.com>
---
 lib/crc32test.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/lib/crc32test.c b/lib/crc32test.c
index 97d6a57cefcc..61ddce2cff77 100644
--- a/lib/crc32test.c
+++ b/lib/crc32test.c
@@ -683,7 +683,6 @@ static int __init crc32c_test(void)
 
 	/* reduce OS noise */
 	local_irq_save(flags);
-	local_irq_disable();
 
 	nsec = ktime_get_ns();
 	for (i = 0; i < 100; i++) {
@@ -694,7 +693,6 @@ static int __init crc32c_test(void)
 	nsec = ktime_get_ns() - nsec;
 
 	local_irq_restore(flags);
-	local_irq_enable();
 
 	pr_info("crc32c: CRC_LE_BITS = %d\n", CRC_LE_BITS);
 
@@ -768,7 +766,6 @@ static int __init crc32_test(void)
 
 	/* reduce OS noise */
 	local_irq_save(flags);
-	local_irq_disable();
 
 	nsec = ktime_get_ns();
 	for (i = 0; i < 100; i++) {
@@ -783,7 +780,6 @@ static int __init crc32_test(void)
 	nsec = ktime_get_ns() - nsec;
 
 	local_irq_restore(flags);
-	local_irq_enable();
 
 	pr_info("crc32: CRC_LE_BITS = %d, CRC_BE BITS = %d\n",
 		 CRC_LE_BITS, CRC_BE_BITS);
-- 
2.25.4