lkml.org 
[lkml]   [2019]   [Jun]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v5 3/3] arm64/fpsimd: Don't disable softirq when touching FPSIMD/SVE state
On Mon, Jun 03, 2019 at 05:25:34PM +0100, Catalin Marinas wrote:
> On Tue, May 21, 2019 at 06:21:39PM +0100, Julien Grall wrote:
> > Since a softirq is supposed to check may_use_simd() anyway before
> > attempting to use FPSIMD/SVE, there is limited reason to keep softirq
> > disabled when touching the FPSIMD/SVE context. Instead, we can simply
> > disable preemption and mark the FPSIMD/SVE context as in use by setting
> > CPU's fpsimd_context_busy flag.
> [...]
> > +static void get_cpu_fpsimd_context(void)
> > +{
> > + preempt_disable();
> > + __get_cpu_fpsimd_context();
> > +}
>
> Is there anything that prevents a softirq being invoked between
> preempt_disable() and __get_cpu_fpsimd_context()?

Actually, it shouldn't matter as the softirq finishes using the fpsimd
before the thread is resumed.

--
Catalin

\
 
 \ /
  Last update: 2019-06-03 23:59    [W:0.068 / U:0.660 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site