commit: 9f85550347f51c79a917b2aec04c90691c11e20a From: Linus Walleij <[email protected]> Date: Tue, 10 Apr 2012 12:37:42 +0100 Subject: ARM: 7359/2: smp_twd: Only wait for reprogramming on active cpus
During booting of cpu1, there is a short window where cpu1 is online, but not active where cpu1 is occupied by waiting to become active. If cpu0 then decides to schedule something on cpu1 and wait for it to complete, before cpu0 has set cpu1 active, we have a deadlock. Typically it's this CPU frequency transition that happens at this time, so let's just not wait for it to happen, it will happen whenever the CPU eventually comes online instead. Cc: Peter Zijlstra <[email protected]> Cc: [email protected] Signed-off-by: Jonas Aaberg <[email protected]> Reviewed-by: Rickard Andersson <[email protected]> Signed-off-by: Linus Walleij <[email protected]> Signed-off-by: Russell King <[email protected]> --- arch/arm/kernel/smp_twd.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c index fef42b2..5b150af 100644 --- a/arch/arm/kernel/smp_twd.c +++ b/arch/arm/kernel/smp_twd.c @@ -118,10 +118,14 @@ static int twd_cpufreq_transition(struct notifier_block *nb, * The twd clock events must be reprogrammed to account for the new * frequency. The timer is local to a cpu, so cross-call to the * changing cpu. + * + * Only wait for it to finish, if the cpu is active to avoid + * deadlock when cpu1 is spinning on while(!cpu_active(cpu1)) during + * booting of that cpu. */ if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE) smp_call_function_single(freqs->cpu, twd_update_frequency, - NULL, 1); + NULL, cpu_active(freqs->cpu)); return NOTIFY_OK; } -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
