From 50c668d678fd01284799a6e4f1b91829d83cb9ed Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 12 Jan 2009 10:49:53 +0100 Subject: [PATCH] Revert "cpumask: use work_on_cpu in acpi-cpufreq.c for drv_read and drv_write" This reverts commit 7503bfbae89eba07b46441a5d1594647f6b8ab7d. Dieter Ries reported bootup soft-hangs and bisected it back to this commit, and reverting this commit gave him a working system. The commit introduces work_on_cpu() use into the cpufreq code, but that is subtly problematic from a lock hierarchy POV: the hotplug-cpu lock is an highlevel lock that is taken before lowlevel locks, and in this codepath we are called with the policy lock taken. Dieter did not have lockdep enabled so we dont have a nice stack trace proof for this, but using work_on_cpu() in such a lowlevel place certainly looks wrong, so we revert the patch. work_on_cpu() needs to be reworked to be more generally usable. Reported-by: Dieter Ries Tested-by: Dieter Ries Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 25 +++++++++++----------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c index 06fcd8f9323..6f11e029e8c 100644 --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c @@ -150,9 +150,8 @@ struct drv_cmd { u32 val; }; -static long do_drv_read(void *_cmd) +static void do_drv_read(struct drv_cmd *cmd) { - struct drv_cmd *cmd = _cmd; u32 h; switch (cmd->type) { @@ -167,12 +166,10 @@ static long do_drv_read(void *_cmd) default: break; } - return 0; } -static long do_drv_write(void *_cmd) +static void do_drv_write(struct drv_cmd *cmd) { - struct drv_cmd *cmd = _cmd; u32 lo, hi; switch (cmd->type) { @@ -189,23 +186,30 @@ static long do_drv_write(void *_cmd) default: break; } - return 0; } static void drv_read(struct drv_cmd *cmd) { + cpumask_t saved_mask = current->cpus_allowed; cmd->val = 0; - work_on_cpu(cpumask_any(cmd->mask), do_drv_read, cmd); + set_cpus_allowed_ptr(current, cmd->mask); + do_drv_read(cmd); + set_cpus_allowed_ptr(current, &saved_mask); } static void drv_write(struct drv_cmd *cmd) { + cpumask_t saved_mask = current->cpus_allowed; unsigned int i; for_each_cpu(i, cmd->mask) { - work_on_cpu(i, do_drv_write, cmd); + set_cpus_allowed_ptr(current, cpumask_of(i)); + do_drv_write(cmd); } + + set_cpus_allowed_ptr(current, &saved_mask); + return; } static u32 get_cur_val(const struct cpumask *mask) @@ -231,15 +235,10 @@ static u32 get_cur_val(const struct cpumask *mask) return 0; } - if (unlikely(!alloc_cpumask_var(&cmd.mask, GFP_KERNEL))) - return 0; - cpumask_copy(cmd.mask, mask); drv_read(&cmd); - free_cpumask_var(cmd.mask); - dprintk("get_cur_val = %u\n", cmd.val); return cmd.val; -- 2.20.1