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Wysocki" , linux-pm@vger.kernel.org, Arjan van de Ven , "Paul E. McKenney" , Frederic Weisbecker , Rik van Riel , Anna-Maria Behnsen Subject: [PATCH v3 02/17] tick-sched: Warn when next tick seems to be in the past Date: Tue, 25 Oct 2022 15:58:35 +0200 Message-Id: <20221025135850.51044-3-anna-maria@linutronix.de> In-Reply-To: <20221025135850.51044-1-anna-maria@linutronix.de> References: <20221025135850.51044-1-anna-maria@linutronix.de> MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747668415675233408?= X-GMAIL-MSGID: =?utf-8?q?1747668415675233408?= When the next tick is in the past, the delta between basemono and the next tick gets negativ. But the next tick should never be in the past. The negative effect of a wrong next tick might be a stop of the tick and timers might expire late. To prevent expensive debugging when changing underlying code, add a WARN_ON_ONCE into this code path. Signed-off-by: Anna-Maria Behnsen Reviewed-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker --- kernel/time/tick-sched.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index b0e3c9205946..7ffdc7ba19b4 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -826,6 +826,8 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu) * If the tick is due in the next period, keep it ticking or * force prod the timer. */ + WARN_ON_ONCE(basemono > next_tick); + delta = next_tick - basemono; if (delta <= (u64)TICK_NSEC) { /*