[PATCH 03/13] drivers/acpi: convert seqno seqnum_ops

[Shuah Khan]

seqnum_ops api is introduced to be used when a variable is used as
a sequence/stat counter and doesn't guard object lifetimes. This
clearly differentiates atomic_t usages that guard object lifetimes.

seqnum32 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. This conversion doesn't
change the overflow wrap around behavior.

Convert it to use seqnum_ops. This conversion replaces inc_return()
with _inc() followed by _read().

Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
---
 drivers/acpi/acpi_extlog.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index 72f1fb77abcd..1e2b36aab9aa 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/seqnum_ops.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 seqnum32 seqno;
 	unsigned int curr_seqno;
 	char pfx_seq[64];
 
@@ -103,7 +104,8 @@ static void __print_extlog_rcd(const char *pfx,
 		else
 			pfx = KERN_ERR;
 	}
-	curr_seqno = atomic_inc_return(&seqno);
+	seqnum32_inc(&seqno);
+	curr_seqno = seqnum32_read(&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);
-- 
2.27.0