Date: Tue, 23 Dec 2014 09:03:48 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Rui Paulo <rpaulo@me.com>, John Baldwin <jhb@FreeBSD.org> Cc: Konstantin Belousov <kostikbel@gmail.com>, svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r276008 - in head/sys: kern sys Message-ID: <549913D4.5090103@FreeBSD.org> In-Reply-To: <2C4635EF-6BE6-4ED7-B9D1-237F76259E88@me.com> References: <201412211332.sBLDW8VC030548@svn.freebsd.org> <201412220940.02509.jhb@freebsd.org> <08A2ABA0-C982-46BC-B309-3C23B8D277B9@me.com> <201412221417.42894.jhb@freebsd.org> <2C4635EF-6BE6-4ED7-B9D1-237F76259E88@me.com>
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On 23/12/2014 04:39, Rui Paulo wrote: > On Dec 22, 2014, at 11:17, John Baldwin <jhb@freebsd.org> wrote: >> >> On Monday, December 22, 2014 1:29:38 pm Rui Paulo wrote: >>> On Dec 22, 2014, at 06:40, John Baldwin <jhb@freebsd.org> wrote: >>>> Is there something specific to core dumps that makes vn_fullpath() more >>>> useful to have working before a process tries to open the core? (As >>>> compared to other newly-created files) >>> >>> Yes: the ability to provide the full path to userland when a core dump file >> is generated. >> >> Can you be more specific? Are we printing the path on the console after >> destroying the generated path? Is it being written into a note in the core >> itself (but only having the vnode of the core file available and not the >> generated path)? > > No. I have some code that calls devctl_notify() when a core dump is generated which is useful for running an automated debugging session. We use this at work and I'll see if I can upstream it. What Konstantin fixed was the generation of the cache entry in the corefile_open() routine. This lets me call vn_fullpath() after vn_close() with a high probability that it will work whereas, in the past, it was never in the cache, so vn_fullpath() would always fail. What is not entirely clear to me is why we need to recover the path from the vnode if we, obviously, have the path even before we have the vnode. -- Andriy Gapon
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