From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 194DE1170E for ; Mon, 11 Sep 2023 13:53:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 89E5AC433C7; Mon, 11 Sep 2023 13:53:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694440416; bh=5V48RBXN2ptguGI4x/4Ja50iDIs27PgkQRgtyRtg+K0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MLS9016Nieneo+rVELnQOLBFi7iY5FW4NwgvtFjdZnFzsTeOTBMRaEpzgsFCPN/Oe sUBQc8T1otMukxnhebkKd9YzT/Usuq765bu9DhD4HxjWz5zG4O/Iq97ZGzr3S2ldRm M/dCOc7aIqEMvDGkbXpjgusAIOk8oCtMsikA+g/A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Bainbridge , Feng Tang , "Paul E. McKenney" , Sasha Levin Subject: [PATCH 6.5 027/739] clocksource: Handle negative skews in "skew is too large" messages Date: Mon, 11 Sep 2023 15:37:06 +0200 Message-ID: <20230911134651.821495178@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230911134650.921299741@linuxfoundation.org> References: <20230911134650.921299741@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul E. McKenney [ Upstream commit e40806e9bcf8aaa86dbf0d484e7cf3cfa09cb86c ] The nanosecond-to-millisecond skew computation uses unsigned arithmetic, which produces user-unfriendly large positive numbers for negative skews. Therefore, use signed arithmetic for this computation in order to preserve the negativity. Reported-by: Chris Bainbridge Reported-by: Feng Tang Fixes: dd029269947a ("clocksource: Improve "skew is too large" messages") Reviewed-by: Feng Tang Tested-by: Chris Bainbridge Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin --- kernel/time/clocksource.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 88cbc1181b239..c108ed8a9804a 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -473,8 +473,8 @@ static void clocksource_watchdog(struct timer_list *unused) /* Check the deviation from the watchdog clocksource. */ md = cs->uncertainty_margin + watchdog->uncertainty_margin; if (abs(cs_nsec - wd_nsec) > md) { - u64 cs_wd_msec; - u64 wd_msec; + s64 cs_wd_msec; + s64 wd_msec; u32 wd_rem; pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", @@ -483,8 +483,8 @@ static void clocksource_watchdog(struct timer_list *unused) watchdog->name, wd_nsec, wdnow, wdlast, watchdog->mask); pr_warn(" '%s' cs_nsec: %lld cs_now: %llx cs_last: %llx mask: %llx\n", cs->name, cs_nsec, csnow, cslast, cs->mask); - cs_wd_msec = div_u64_rem(cs_nsec - wd_nsec, 1000U * 1000U, &wd_rem); - wd_msec = div_u64_rem(wd_nsec, 1000U * 1000U, &wd_rem); + cs_wd_msec = div_s64_rem(cs_nsec - wd_nsec, 1000 * 1000, &wd_rem); + wd_msec = div_s64_rem(wd_nsec, 1000 * 1000, &wd_rem); pr_warn(" Clocksource '%s' skewed %lld ns (%lld ms) over watchdog '%s' interval of %lld ns (%lld ms)\n", cs->name, cs_nsec - wd_nsec, cs_wd_msec, watchdog->name, wd_nsec, wd_msec); if (curr_clocksource == cs) -- 2.40.1