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Date: Thu, 2 Nov 2017 08:32:00 -0500 From: Josh Poimboeuf <jpoimboe@...hat.com> To: Miroslav Benes <mbenes@...e.cz> Cc: jeyu@...nel.org, jikos@...nel.org, pmladek@...e.com, lpechacek@...e.cz, pavel@....cz, live-patching@...r.kernel.org, linux-kernel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>, Michael Ellerman <mpe@...erman.id.au>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, linuxppc-dev@...ts.ozlabs.org, x86@...nel.org Subject: Re: [PATCH v3 1/2] livepatch: send a fake signal to all blocking tasks On Tue, Oct 31, 2017 at 12:48:52PM +0100, Miroslav Benes wrote: > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > index bf8c8fd72589..b7c60662baf3 100644 > --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -440,6 +440,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch); > * /sys/kernel/livepatch/<patch> > * /sys/kernel/livepatch/<patch>/enabled > * /sys/kernel/livepatch/<patch>/transition > + * /sys/kernel/livepatch/<patch>/signal > * /sys/kernel/livepatch/<patch>/<object> > * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> > */ > @@ -514,11 +515,37 @@ static ssize_t transition_show(struct kobject *kobj, > patch == klp_transition_patch); > } > > +static ssize_t signal_store(struct kobject *kobj, struct kobj_attribute *attr, > + const char *buf, size_t count) > +{ > + int ret; > + bool val; > + > + /* > + * klp_mutex lock is not grabbed here intentionally. It is not really > + * needed. The race window is harmless and grabbing the lock would only > + * hold the action back. > + */ > + if (!klp_transition_patch) > + return -EINVAL; > + > + ret = kstrtobool(buf, &val); > + if (ret) > + return ret; > + > + if (val) > + klp_force_signals(); > + > + return count; > +} The function still has global functionality even though the sysfs entry is now per-patch. So if you do echo 1 > /sys/kernel/livepatch/patch1/signal But patch2 is in transition, then it will send signals based on patch2. Instead it should probably return an error. There's a similar issue with force_store(). -- Josh
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