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From: Junio C Hamano <gitster@pobox•com>
To: Jeff King <peff@peff•net>
Cc: Takashi Iwai <tiwai@suse•de>,
	Andreas Schwab <schwab@linux-m68k•org>,
	git@vger•kernel.org
Subject: Re: glibc mutex deadlock in signal handler
Date: Fri, 04 Sep 2015 14:56:58 -0700	[thread overview]
Message-ID: <xmqq7fo5g85x.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <20150904092355.GA524@sigill.intra.peff.net> (Jeff King's message of "Fri, 4 Sep 2015 05:23:55 -0400")

Jeff King <peff@peff•net> writes:

> Perhaps we should reconsider whether f4c3edc (vreportf: avoid
> intermediate buffer, 2015-08-11) is a good idea.  Note that snprintf is
> not on the list of safe functions, but I imagine that in practice it is
> fine. Though just avoiding error()/warning() in signal handlers might be
> a more practical solution anyway.

I had exactly the same thought when I read the initial report here.

I wish we can just do "if (in_signal) return;" at the beginning of
vreportf(), but we would not want a global variable there, so... ;-)

Further, I briefly hoped that avoiding error/warning in the signal
handler codepath would allow us to be more lax around allocations,
but I suspect that it unfortunately would not help us that much, as
we may be calling these functions in low memory situations.

So let's queue Takashi's patch as-is for now and look at other
signal codepaths.

Thanks.

	
	

next prev parent reply	other threads:[~2015-09-04 21:57 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-03 11:00 glibc mutex deadlock in signal handler Takashi Iwai
2015-09-03 18:12 ` Junio C Hamano
2015-09-03 19:34   ` Takashi Iwai
2015-09-03 20:55     ` Andreas Schwab
2015-09-04  5:52       ` Takashi Iwai
2015-09-04  9:23         ` Jeff King
2015-09-04  9:35           ` Takashi Iwai
2015-09-04 13:04             ` Jeff King
2015-09-04 13:40               ` Takashi Iwai
2015-09-04 21:56           ` Junio C Hamano [this message]
2015-09-05  8:59             ` Jeff King

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