linux-kernel - [PATCH v3 06/11] drivers/acpi/apei: convert seqno counter

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Message-Id: <2f39e13e92b587ac48b7c11a17854b6426cfb745.1602209970.git.skhan@linuxfoundation.org>
Date:   Fri,  9 Oct 2020 09:56:01 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     rafael@...nel.org, james.morse@....com, tony.luck@...el.com,
        bp@...en8.de, gregkh@...uxfoundation.org, keescook@...omium.org
Cc:     Shuah Khan <skhan@...uxfoundation.org>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>
Subject: [PATCH v3 06/11] drivers/acpi/apei: convert seqno counter_atomic32

counter_atomic* is introduced to be used when a variable is used as
a simple counter and doesn't guard object lifetimes. This clearly
differentiates atomic_t usages that guard object lifetimes.

counter_atomic* variables wrap around to INT_MIN when it overflows
and should not be used to guard resource lifetimes, device usage and
open counts that control state changes, and pm states.

seqno is a sequence number counter for logging. This counter gets
incremented. Unsure if there is a chance of this overflowing. It
doesn't look like overflowing causes any problems since it is used
to tag the log messages and nothing more.

Convert it to use counter_atomic32.

This conversion doesn't change the overflow wrap around behavior.

Acked-by: Rafael J. Wysocki <rafael@...nel.org>
Acked-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
---
 drivers/acpi/apei/ghes.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 81bf71b10d44..92169436be18 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -41,6 +41,7 @@
 #include <linux/uuid.h>
 #include <linux/ras.h>
 #include <linux/task_work.h>
+#include <linux/counters.h>
 
 #include <acpi/actbl1.h>
 #include <acpi/ghes.h>
@@ -562,7 +563,7 @@ static void __ghes_print_estatus(const char *pfx,
 				 const struct acpi_hest_generic *generic,
 				 const struct acpi_hest_generic_status *estatus)
 {
-	static atomic_t seqno;
+	static struct counter_atomic32 seqno = COUNTER_ATOMIC_INIT(0);
 	unsigned int curr_seqno;
 	char pfx_seq[64];
 
@@ -573,7 +574,7 @@ static void __ghes_print_estatus(const char *pfx,
 		else
 			pfx = KERN_ERR;
 	}
-	curr_seqno = atomic_inc_return(&seqno);
+	curr_seqno = counter_atomic32_inc_return(&seqno);
 	snprintf(pfx_seq, sizeof(pfx_seq), "%s{%u}" HW_ERR, pfx, curr_seqno);
 	printk("%s""Hardware error from APEI Generic Hardware Error Source: %d\n",
 	       pfx_seq, generic->header.source_id);
-- 
2.25.1