linux-kernel - [PATCH 5.4 107/141] hwmon: (occ) Fix poll rate limiting

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Message-Id: <20210517140246.394625648@linuxfoundation.org>
Date:   Mon, 17 May 2021 16:02:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eddie James <eajames@...ux.ibm.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 107/141] hwmon: (occ) Fix poll rate limiting

From: Eddie James <eajames@...ux.ibm.com>

[ Upstream commit 5216dff22dc2bbbbe6f00335f9fd2879670e753b ]

The poll rate limiter time was initialized at zero. This breaks the
comparison in time_after if jiffies is large. Switch to storing the
next update time rather than the previous time, and initialize the
time when the device is probed.

Fixes: c10e753d43eb ("hwmon (occ): Add sensor types and versions")
Signed-off-by: Eddie James <eajames@...ux.ibm.com>
Link: https://lore.kernel.org/r/20210429151336.18980-1-eajames@linux.ibm.com
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/hwmon/occ/common.c | 5 +++--
 drivers/hwmon/occ/common.h | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
index 30e18eb60da7..0b689ccbb793 100644
--- a/drivers/hwmon/occ/common.c
+++ b/drivers/hwmon/occ/common.c
@@ -209,9 +209,9 @@ int occ_update_response(struct occ *occ)
 		return rc;
 
 	/* limit the maximum rate of polling the OCC */
-	if (time_after(jiffies, occ->last_update + OCC_UPDATE_FREQUENCY)) {
+	if (time_after(jiffies, occ->next_update)) {
 		rc = occ_poll(occ);
-		occ->last_update = jiffies;
+		occ->next_update = jiffies + OCC_UPDATE_FREQUENCY;
 	} else {
 		rc = occ->last_error;
 	}
@@ -1089,6 +1089,7 @@ int occ_setup(struct occ *occ, const char *name)
 		return rc;
 	}
 
+	occ->next_update = jiffies + OCC_UPDATE_FREQUENCY;
 	occ_parse_poll_response(occ);
 
 	rc = occ_setup_sensor_attrs(occ);
diff --git a/drivers/hwmon/occ/common.h b/drivers/hwmon/occ/common.h
index 67e6968b8978..e6df719770e8 100644
--- a/drivers/hwmon/occ/common.h
+++ b/drivers/hwmon/occ/common.h
@@ -99,7 +99,7 @@ struct occ {
 	u8 poll_cmd_data;		/* to perform OCC poll command */
 	int (*send_cmd)(struct occ *occ, u8 *cmd);
 
-	unsigned long last_update;
+	unsigned long next_update;
 	struct mutex lock;		/* lock OCC access */
 
 	struct device *hwmon;
-- 
2.30.2