Thomas Gleixner writes:
> While trying to address the longstanding FIXME in the posix timer code
> related to ignored signals, I stumbled over the following issue:
>
> I blocked the signal of the timer, then installed the SIG_IGN handler,
> created and started the timer. After a short sleep the t
Hi Thomas,
On 05/30/2017 03:21 PM, Thomas Gleixner wrote:
> While trying to address the longstanding FIXME in the posix timer code
> related to ignored signals, I stumbled over the following issue:
>
> I blocked the signal of the timer, then installed the SIG_IGN handler,
> created and started th
ebied...@xmission.com (Eric W. Biederman) writes:
> Thomas Gleixner writes:
>
>> On Tue, 30 May 2017, Linus Torvalds wrote:
>>> On Tue, May 30, 2017 at 10:04 AM, Oleg Nesterov wrote:
>>> > Obviously this is a user-visible change and it can break something. Say,
>>> > an
>>> > application does s
Thomas Gleixner writes:
> On Tue, 30 May 2017, Linus Torvalds wrote:
>> On Tue, May 30, 2017 at 10:04 AM, Oleg Nesterov wrote:
>> > Obviously this is a user-visible change and it can break something. Say, an
>> > application does sigwaitinfo(SIGCHLD) and SIGCHLD is ignored (SIG_IGN),
>> > this
On Tue, 30 May 2017, Linus Torvalds wrote:
> On Tue, May 30, 2017 at 12:35 PM, Thomas Gleixner wrote:
> > The reason why I'm looking into that is the silly case with posix interval
> > timers dealing with ignored signals. We have to keep these timers self
> > rearming because nothing rearms them w
On Tue, 30 May 2017, Linus Torvalds wrote:
> On Tue, May 30, 2017 at 10:04 AM, Oleg Nesterov wrote:
> > Obviously this is a user-visible change and it can break something. Say, an
> > application does sigwaitinfo(SIGCHLD) and SIGCHLD is ignored (SIG_IGN), this
> > will no longer work.
>
> That's
On Tue, May 30, 2017 at 12:35 PM, Thomas Gleixner wrote:
> Right, blocking signals which are not set to SIG_IGN makes perfectly sense.
> The
> SIG_IGN case is what bothers me.
The thing is, the SIG_IGN may not *remain* a SIG_IGN.
Put another way, let's say that you are a process that uses signa
On Tue, 30 May 2017, Linus Torvalds wrote:
> On Tue, May 30, 2017 at 6:21 AM, Thomas Gleixner wrote:
> >
> > Linus, any recollection?
> >
> > IMO, it's perfectly reasonable to discard ignored signals even when the
> > signal is in the blocked mask. When its unblocked and SIG_IGN is replaced
> > th
On 05/30, Linus Torvalds wrote:
>
> On Tue, May 30, 2017 at 10:04 AM, Oleg Nesterov wrote:
> >
> > I can't comment, I never tried to understand the rationality behind the
> > current
> > behaviour. But at least the sending path should never drop a blocked SIG_DFL
> > signal, there is no other way
On Tue, May 30, 2017 at 10:04 AM, Oleg Nesterov wrote:
>
> I can't comment, I never tried to understand the rationality behind the
> current
> behaviour. But at least the sending path should never drop a blocked SIG_DFL
> signal, there is no other way to ensure you won't miss a signal during exec
On 05/30, Thomas Gleixner wrote:
>
> So I found at least some explanation by studying the spec some more.
>
> There are two variants of ignored signals:
>
> 1) handler is SIG_IGN
>
> 2) handler is SIG_DFL and default action is 'ignore'
Yes, and note that sys_rt_sigaction() discard the pending
On Tue, May 30, 2017 at 6:21 AM, Thomas Gleixner wrote:
>
> Linus, any recollection?
>
> IMO, it's perfectly reasonable to discard ignored signals even when the
> signal is in the blocked mask. When its unblocked and SIG_IGN is replaced
> then the next signal will be delivered. But hell knows, how
On Tue, 30 May 2017, Thomas Gleixner wrote:
> The commit which added the queuing of blocked and ignored signals is in the
> history tree with a pretty useless changelog.
>
> https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
>
> commit 98fc8ab9e74389e0c7001052597f61336dc62833
> Au
While trying to address the longstanding FIXME in the posix timer code
related to ignored signals, I stumbled over the following issue:
I blocked the signal of the timer, then installed the SIG_IGN handler,
created and started the timer. After a short sleep the timer has fired
several times, but i
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