lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 4 Nov 2014 11:20:21 -0500 From: Don Zickus <dzickus@...hat.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>, uobergfe@...hat.com, Don Zickus <dzickus@...hat.com> Subject: [PATCH 6/9] watchdog: implement error handling for failure to set up hardware perf events From: Ulrich Obergfell <uobergfe@...hat.com> If watchdog_nmi_enable() fails to set up the hardware perf event of one CPU, the entire hard lockup detector is deemed unreliable. Hence, disable the hard lockup detector and shut down the hardware perf events on all CPUs. Signed-off-by: Ulrich Obergfell <uobergfe@...hat.com> Signed-off-by: Don Zickus <dzickus@...hat.com> --- kernel/watchdog.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 2897a5e..86ba5e5 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -502,6 +502,15 @@ static void watchdog(unsigned int cpu) __this_cpu_write(soft_lockup_hrtimer_cnt, __this_cpu_read(hrtimer_interrupts)); __touch_watchdog(); + + /* + * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the + * failure path. Check for failures that can occur asynchronously - + * for example, when CPUs are on-lined - and shut down the hardware + * perf event on each CPU accordingly. + */ + if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) + watchdog_nmi_disable(cpu); } #ifdef CONFIG_HARDLOCKUP_DETECTOR @@ -552,6 +561,15 @@ handle_err: goto out_save; } + /* + * Disable the hard lockup detector if _any_ CPU fails to set up + * set up the hardware perf event. The watchdog() function checks + * the NMI_WATCHDOG_ENABLED bit periodically. + */ + smp_mb__before_atomic(); + clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled); + smp_mb__after_atomic(); + /* skip displaying the same error again */ if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) return PTR_ERR(event); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists