diff mbox series

[v2,06/11] drivers/acpi/apei: convert seqno counter_atomic32

Message ID 884f1fddfbc1a991f5f5bbada3ea63c1e3afab20.1602011710.git.skhan@linuxfoundation.org (mailing list archive)
State Not Applicable, archived
Headers show
Series Introduce Simple atomic counters | expand

Commit Message

Shuah Khan Oct. 6, 2020, 8:44 p.m. UTC 
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 will wrap around to 0 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@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
 drivers/acpi/apei/ghes.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Kees Cook Oct. 7, 2020, 6:17 p.m. UTC | #1 
On Tue, Oct 06, 2020 at 02:44:37PM -0600, Shuah Khan wrote:
> 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 will wrap around to 0 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@kernel.org>
> Acked-by: Borislav Petkov <bp@suse.de>
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Yup, also logging only, it seems.

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

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);