From: Peter Zijlstra <peterz@infradead.org>
To: Juergen Gross <jgross@suse.com>
Cc: x86@kernel.org, jdelvare@suse.com, hpa@zytor.com,
linux-kernel@vger.kernel.org, mingo@redhat.com,
david.vrabel@citrix.com, Douglas_Warzecha@dell.com,
pali.rohar@gmail.com, xen-devel@lists.xenproject.org,
boris.ostrovsky@oracle.com, tglx@linutronix.de,
linux@roeck-us.net
Subject: Re: [PATCH 2/6] sched: add function to execute a function synchronously on a physical cpu
Date: Fri, 11 Mar 2016 13:42:38 +0100 [thread overview]
Message-ID: <20160311124238.GN6375__32372.7219285958$1457700237$gmane$org@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160311121950.GZ6344@twins.programming.kicks-ass.net>
On Fri, Mar 11, 2016 at 01:19:50PM +0100, Peter Zijlstra wrote:
> On Fri, Mar 11, 2016 at 12:59:30PM +0100, Juergen Gross wrote:
> > +int call_sync_on_phys_cpu(unsigned cpu, int (*func)(void *), void *par)
> > +{
> > + cpumask_var_t old_mask;
> > + int ret;
> > +
> > + if (cpu >= nr_cpu_ids)
> > + return -EINVAL;
> > +
> > + if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
> > + return -ENOMEM;
> > +
> > + cpumask_copy(old_mask, ¤t->cpus_allowed);
> > + ret = set_cpus_allowed_ptr(current, cpumask_of(cpu));
> > + if (ret)
> > + goto out;
>
> So what happens if someone does sched_setaffinity() right about here?
>
> > +
> > + ret = func(par);
> > +
> > + set_cpus_allowed_ptr(current, old_mask);
> > +
> > +out:
> > + free_cpumask_var(old_mask);
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(call_sync_on_phys_cpu);
>
> This is disgusting, and you're adding this to !Xen kernels too.
how about something like:
struct xen_callback_struct {
struct work_struct work;
struct completion done;
void * data;
int ret;
};
static void xen_callback_f(struct work_struct *work)
{
struct xen_callback_struct *xcs = container_of(work, struct xen_callback_struct, work);
xcs->ret = xcs->func(xcs->data);
complete(&xcs->done);
}
xen_call_on_cpu_sync(int cpu, int (*func)(void *), void *data)
{
struct xen_callback_state xcs = {
.work = __WORK_INITIALIZER(xcs.work, xen_callback_f);
.done = COMPLETION_INITIALIZER_ONSTACK(xcs.done),
.data = data,
};
queue_work_on(&work, cpu);
wait_for_completion(&xcs.done);
return xcs.ret;
}
No mucking about with the scheduler state, no new exported functions
etc..
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2016-03-11 12:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1457697574-6710-1-git-send-email-jgross@suse.com>
2016-03-11 11:59 ` [PATCH 1/6] xen: sync xen header Juergen Gross
2016-03-11 11:59 ` [PATCH 2/6] sched: add function to execute a function synchronously on a physical cpu Juergen Gross
2016-03-11 11:59 ` [PATCH 3/6] dcdbas: make use of call_sync_on_phys_cpu() Juergen Gross
2016-03-11 11:59 ` [PATCH 4/6] hwmon: use call_sync_on_phys_cpu() for dell-smm i8k Juergen Gross
2016-03-11 11:59 ` [PATCH 5/6] virt, sched: add cpu pinning to call_sync_on_phys_cpu() Juergen Gross
2016-03-11 11:59 ` [PATCH 6/6] xen: add xen_pin_vcpu() to support calling functions on a dedicated pcpu Juergen Gross
[not found] ` <1457697574-6710-3-git-send-email-jgross@suse.com>
2016-03-11 12:19 ` [PATCH 2/6] sched: add function to execute a function synchronously on a physical cpu Peter Zijlstra
[not found] ` <20160311121950.GZ6344@twins.programming.kicks-ass.net>
2016-03-11 12:42 ` Peter Zijlstra [this message]
2016-03-11 12:43 ` Juergen Gross
[not found] ` <56E2BD89.4020400@suse.com>
2016-03-11 12:45 ` Peter Zijlstra
[not found] ` <20160311124238.GN6375@twins.programming.kicks-ass.net>
2016-03-11 12:48 ` Juergen Gross
[not found] ` <56E2BE8C.9030309@suse.com>
2016-03-11 12:57 ` Peter Zijlstra
[not found] ` <20160311125706.GC6344@twins.programming.kicks-ass.net>
2016-03-11 13:07 ` Juergen Gross
2016-03-11 12:25 ` [PATCH 0/6] Support calling functions on dedicated " Peter Zijlstra
[not found] ` <20160311122514.GA6344@twins.programming.kicks-ass.net>
2016-03-11 12:28 ` Pali Rohár
2016-03-11 13:15 ` One Thousand Gnomes
2016-03-11 13:19 ` Peter Zijlstra
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