From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Zhou Ti (x2019cwm)" <x2019cwm@stfx.ca>
Subject: [PATCH v1 2/5] cpuidle: Use s64 as exit_latency_ns and target_residency_ns data type
Date: Mon, 29 Mar 2021 20:15:19 +0200 [thread overview]
Message-ID: <1850839.PYKUYFuaPT@kreacher> (raw)
In-Reply-To: <2764850.e9J7NaK4W3@kreacher>
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subsequent changes will cause the exit_latency_ns and target_residency_ns
fields in struct cpuidle_state to be used in computations in which data
type conversions to u64 may turn a negative number close to zero into
a verly large positive number leading to incorrect results.
In preparation for that, change the data type of the fields mentioned
above to s64, but ensure that they will not be negative themselves.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/cpuidle/driver.c | 4 ++++
include/linux/cpuidle.h | 4 ++--
2 files changed, 6 insertions(+), 2 deletions(-)
Index: linux-pm/include/linux/cpuidle.h
===================================================================
--- linux-pm.orig/include/linux/cpuidle.h
+++ linux-pm/include/linux/cpuidle.h
@@ -49,8 +49,8 @@ struct cpuidle_state {
char name[CPUIDLE_NAME_LEN];
char desc[CPUIDLE_DESC_LEN];
- u64 exit_latency_ns;
- u64 target_residency_ns;
+ s64 exit_latency_ns;
+ s64 target_residency_ns;
unsigned int flags;
unsigned int exit_latency; /* in US */
int power_usage; /* in mW */
Index: linux-pm/drivers/cpuidle/driver.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/driver.c
+++ linux-pm/drivers/cpuidle/driver.c
@@ -181,9 +181,13 @@ static void __cpuidle_driver_init(struct
*/
if (s->target_residency > 0)
s->target_residency_ns = s->target_residency * NSEC_PER_USEC;
+ else if (s->target_residency_ns < 0)
+ s->target_residency_ns = 0;
if (s->exit_latency > 0)
s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC;
+ else if (s->exit_latency_ns < 0)
+ s->exit_latency_ns = 0;
}
}
next prev parent reply other threads:[~2021-03-29 18:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-29 18:12 [PATCH v1 0/5] cpuidle: Take possible negative "sleep length" values into account Rafael J. Wysocki
2021-03-29 18:13 ` [PATCH v1 1/5] tick/nohz: Improve tick_nohz_get_next_hrtimer() kerneldoc Rafael J. Wysocki
2021-03-29 18:15 ` Rafael J. Wysocki [this message]
2021-03-29 18:19 ` [PATCH v1 3/5] cpuidle: teo: Adjust handling of very short idle times Rafael J. Wysocki
2021-03-29 18:21 ` [PATCH v1 4/5] cpuidle: teo: Take negative "sleep length" values into account Rafael J. Wysocki
2021-03-29 18:37 ` [PATCH v1 5/5] cpuidle: menu: " Rafael J. Wysocki
2021-03-30 1:59 ` Zhou Ti (x2019cwm)
2021-03-30 14:47 ` Rafael J. Wysocki
2021-04-07 17:24 ` [PATCH v1 0/5] cpuidle: Take possible " Rafael J. Wysocki
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