[PATCH 06/13] drivers/char/ipmi: convert stats to use 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.

atomic_t variables used for stats are atomic counters. Overflow will
wrap around and reset the stats and no change with the conversion.

Convert them to use seqnum_ops.

Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
---
 drivers/char/ipmi/ipmi_msghandler.c | 9 +++++----
 drivers/char/ipmi/ipmi_si_intf.c    | 9 +++++----
 drivers/char/ipmi/ipmi_ssif.c       | 9 +++++----
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 8774a3b8ff95..a8f03b4dade9 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -35,6 +35,7 @@
 #include <linux/nospec.h>
 #include <linux/vmalloc.h>
 #include <linux/delay.h>
+#include <linux/seqnum_ops.h>
 
 #define IPMI_DRIVER_VERSION "39.2"
 
@@ -587,7 +588,7 @@ struct ipmi_smi {
 	struct ipmi_my_addrinfo addrinfo[IPMI_MAX_CHANNELS];
 	bool channels_ready;
 
-	atomic_t stats[IPMI_NUM_STATS];
+	struct seqnum32 stats[IPMI_NUM_STATS];
 
 	/*
 	 * run_to_completion duplicate of smb_info, smi_info
@@ -633,9 +634,9 @@ static LIST_HEAD(smi_watchers);
 static DEFINE_MUTEX(smi_watchers_mutex);
 
 #define ipmi_inc_stat(intf, stat) \
-	atomic_inc(&(intf)->stats[IPMI_STAT_ ## stat])
+	seqnum32_inc(&(intf)->stats[IPMI_STAT_ ## stat])
 #define ipmi_get_stat(intf, stat) \
-	((unsigned int) atomic_read(&(intf)->stats[IPMI_STAT_ ## stat]))
+	((unsigned int) seqnum32_read(&(intf)->stats[IPMI_STAT_ ## stat]))
 
 static const char * const addr_src_to_str[] = {
 	"invalid", "hotmod", "hardcoded", "SPMI", "ACPI", "SMBIOS", "PCI",
@@ -3468,7 +3469,7 @@ int ipmi_add_smi(struct module         *owner,
 	INIT_LIST_HEAD(&intf->cmd_rcvrs);
 	init_waitqueue_head(&intf->waitq);
 	for (i = 0; i < IPMI_NUM_STATS; i++)
-		atomic_set(&intf->stats[i], 0);
+		seqnum32_set(&intf->stats[i], 0);
 
 	mutex_lock(&ipmi_interfaces_mutex);
 	/* Look for a hole in the numbers. */
diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 5eac94cf4ff8..e1354076a58a 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -43,6 +43,7 @@
 #include "ipmi_si_sm.h"
 #include <linux/string.h>
 #include <linux/ctype.h>
+#include <linux/seqnum_ops.h>
 
 /* Measure times between events in the driver. */
 #undef DEBUG_TIMING
@@ -237,7 +238,7 @@ struct smi_info {
 	bool dev_group_added;
 
 	/* Counters and things for the proc filesystem. */
-	atomic_t stats[SI_NUM_STATS];
+	struct seqnum32 stats[SI_NUM_STATS];
 
 	struct task_struct *thread;
 
@@ -245,9 +246,9 @@ struct smi_info {
 };
 
 #define smi_inc_stat(smi, stat) \
-	atomic_inc(&(smi)->stats[SI_STAT_ ## stat])
+	seqnum32_inc(&(smi)->stats[SI_STAT_ ## stat])
 #define smi_get_stat(smi, stat) \
-	((unsigned int) atomic_read(&(smi)->stats[SI_STAT_ ## stat]))
+	((unsigned int) seqnum32_read(&(smi)->stats[SI_STAT_ ## stat]))
 
 #define IPMI_MAX_INTFS 4
 static int force_kipmid[IPMI_MAX_INTFS];
@@ -2030,7 +2031,7 @@ static int try_smi_init(struct smi_info *new_smi)
 	atomic_set(&new_smi->req_events, 0);
 	new_smi->run_to_completion = false;
 	for (i = 0; i < SI_NUM_STATS; i++)
-		atomic_set(&new_smi->stats[i], 0);
+		seqnum32_set(&new_smi->stats[i], 0);
 
 	new_smi->interrupt_disabled = true;
 	atomic_set(&new_smi->need_watch, 0);
diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
index 0416b9c9d410..0e61e072b213 100644
--- a/drivers/char/ipmi/ipmi_ssif.c
+++ b/drivers/char/ipmi/ipmi_ssif.c
@@ -47,6 +47,7 @@
 #include <linux/acpi.h>
 #include <linux/ctype.h>
 #include <linux/time64.h>
+#include <linux/seqnum_ops.h>
 #include "ipmi_dmi.h"
 
 #define DEVICE_NAME "ipmi_ssif"
@@ -286,13 +287,13 @@ struct ssif_info {
 	unsigned int  multi_len;
 	unsigned int  multi_pos;
 
-	atomic_t stats[SSIF_NUM_STATS];
+	struct seqnum32 stats[SSIF_NUM_STATS];
 };
 
 #define ssif_inc_stat(ssif, stat) \
-	atomic_inc(&(ssif)->stats[SSIF_STAT_ ## stat])
+	seqnum32_inc(&(ssif)->stats[SSIF_STAT_ ## stat])
 #define ssif_get_stat(ssif, stat) \
-	((unsigned int) atomic_read(&(ssif)->stats[SSIF_STAT_ ## stat]))
+	((unsigned int) seqnum32_read(&(ssif)->stats[SSIF_STAT_ ## stat]))
 
 static bool initialized;
 static bool platform_registered;
@@ -1864,7 +1865,7 @@ static int ssif_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	timer_setup(&ssif_info->watch_timer, watch_timeout, 0);
 
 	for (i = 0; i < SSIF_NUM_STATS; i++)
-		atomic_set(&ssif_info->stats[i], 0);
+		seqnum32_set(&ssif_info->stats[i], 0);
 
 	if (ssif_info->supports_pec)
 		ssif_info->client->flags |= I2C_CLIENT_PEC;
-- 
2.27.0