linux-kernel - [RFC PATCH 09/11] drivers/char/ipmi: convert stats to use counter

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Message-Id: <4d4e8e16549a770cdb97c48886502db0ed5a03ea.1600816121.git.skhan@linuxfoundation.org>
Date:   Tue, 22 Sep 2020 19:43:38 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     minyard@....org, arnd@...db.de, gregkh@...uxfoundation.org,
        keescook@...omium.org
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH 09/11] drivers/char/ipmi: convert stats to use counter_atomic

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.

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 counter_atomic.

Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
---
 drivers/char/ipmi/ipmi_msghandler.c | 9 +++++----
 drivers/char/ipmi/ipmi_si_intf.c    | 9 +++++----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 737c0b6b24ea..c3ad8edd1da3 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -34,6 +34,7 @@
 #include <linux/uuid.h>
 #include <linux/nospec.h>
 #include <linux/vmalloc.h>
+#include <linux/counters.h>
 
 #define IPMI_DRIVER_VERSION "39.2"
 
@@ -584,7 +585,7 @@ struct ipmi_smi {
 	struct ipmi_my_addrinfo addrinfo[IPMI_MAX_CHANNELS];
 	bool channels_ready;
 
-	atomic_t stats[IPMI_NUM_STATS];
+	struct counter_atomic stats[IPMI_NUM_STATS];
 
 	/*
 	 * run_to_completion duplicate of smb_info, smi_info
@@ -630,9 +631,9 @@ static LIST_HEAD(smi_watchers);
 static DEFINE_MUTEX(smi_watchers_mutex);
 
 #define ipmi_inc_stat(intf, stat) \
-	atomic_inc(&(intf)->stats[IPMI_STAT_ ## stat])
+	counter_atomic_inc(&(intf)->stats[IPMI_STAT_ ## stat])
 #define ipmi_get_stat(intf, stat) \
-	((unsigned int) atomic_read(&(intf)->stats[IPMI_STAT_ ## stat]))
+	((unsigned int) counter_atomic_read(&(intf)->stats[IPMI_STAT_ ## stat]))
 
 static const char * const addr_src_to_str[] = {
 	"invalid", "hotmod", "hardcoded", "SPMI", "ACPI", "SMBIOS", "PCI",
@@ -3448,7 +3449,7 @@ 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);
+		counter_atomic_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 77b8d551ae7f..cea1131f7639 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/counters.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 counter_atomic 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])
+	counter_atomic_inc(&(smi)->stats[SI_STAT_ ## stat])
 #define smi_get_stat(smi, stat) \
-	((unsigned int) atomic_read(&(smi)->stats[SI_STAT_ ## stat]))
+	((unsigned int) counter_atomic_read(&(smi)->stats[SI_STAT_ ## stat]))
 
 #define IPMI_MAX_INTFS 4
 static int force_kipmid[IPMI_MAX_INTFS];
@@ -2013,7 +2014,7 @@ 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);
+		counter_atomic_set(&new_smi->stats[i], 0);
 
 	new_smi->interrupt_disabled = true;
 	atomic_set(&new_smi->need_watch, 0);
-- 
2.25.1