[PATCH v3 05/11] drivers/acpi: convert seqno counter_atomic32

Shuah Khan
2020-10-09T15:56:31Z

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@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
drivers/acpi/acpi_extlog.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index f138e12b7b82..d1e733f15cf5 100644
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -12,6 +12,7 @@
#include <linux/ratelimit.h>
#include <linux/edac.h>
#include <linux/ras.h>
+#include <linux/counters.h>
#include <asm/cpu.h>
#include <asm/mce.h>

@@ -93,7 +94,7 @@ static struct acpi_hest_generic_status *extlog_elog_entry_check(int cpu, int ban
static void __print_extlog_rcd(const char *pfx,
struct acpi_hest_generic_status *estatus, int cpu)
{
- static atomic_t seqno;
+ static struct counter_atomic32 seqno;
unsigned int curr_seqno;
char pfx_seq[64];

@@ -103,7 +104,7 @@ static void __print_extlog_rcd(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}", pfx, curr_seqno);
printk("%s""Hardware error detected on CPU%d\n", pfx_seq, cpu);
cper_estatus_print(pfx_seq, estatus);
--
2.25.1