Hi Borislav,
Thank you very much for your review.
On 12/7/2020 10:29 AM, Borislav Petkov wrote:
On Thu, Dec 03, 2020 at 03:25:48PM -0800, Reinette Chatre wrote:
From: Fenghua Yu fenghua.yu@intel.com
The code of setting the CPU on which a task is running in a CPU mask is moved into a couple of helpers.
Pls read section "2) Describe your changes" in Documentation/process/submitting-patches.rst for more details.
More specifically:
"Describe your changes in imperative mood, e.g. "make xyzzy do frotz" instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy to do frotz", as if you are giving orders to the codebase to change its behaviour."
The new helper task_on_cpu() will be reused shortly.
"reused shortly"? I don't think so.
How about: "Move the setting of the CPU on which a task is running in a CPU mask into a couple of helpers.
There is no functional change. This is a preparatory change for the fix in the following patch from where the Fixes tag is copied."
Signed-off-by: Fenghua Yu fenghua.yu@intel.com Signed-off-by: Reinette Chatre reinette.chatre@intel.com Reviewed-by: Tony Luck tony.luck@intel.com Cc: stable@vger.kernel.org
Fixes?
I guess the same commit from the other two:
Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files")
?
Correct. I will add it. The addition to the commit message above aims to explain a Fixes tag to a patch with no functional changes.
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 47 +++++++++++++++++++------- 1 file changed, 34 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index 6f4ca4bea625..68db7d2dec8f 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -525,6 +525,38 @@ static void rdtgroup_remove(struct rdtgroup *rdtgrp) kfree(rdtgrp); } +#ifdef CONFIG_SMP +/* Get the CPU if the task is on it. */ +static bool task_on_cpu(struct task_struct *t, int *cpu) +{
- /*
* This is safe on x86 w/o barriers as the ordering of writing to* task_cpu() and t->on_cpu is reverse to the reading here. The* detection is inaccurate as tasks might move or schedule before* the smp function call takes place. In such a case the function* call is pointless, but there is no other side effect.*/- if (t->on_cpu) {
*cpu = task_cpu(t);Why have an I/O parameter when you can make it simply:
static int task_on_cpu(struct task_struct *t) { if (t->on_cpu) return task_cpu(t);
return -1; }
return true;- }
- return false;
+}
+static void set_task_cpumask(struct task_struct *t, struct cpumask *mask) +{
- int cpu;
- if (mask && task_on_cpu(t, &cpu))
cpumask_set_cpu(cpu, mask);And that you can turn into:
if (!mask) return;
cpu = task_on_cpu(t); if (cpu < 0) return;
cpumask_set_cpu(cpu, mask);
Readable and simple.
Hmm?
Will do. Thank you very much.
Reinette