Date: Thu, 30 Jan 2020 22:09:45 +0100 From: Hans Petter Selasky <hps@selasky.org> To: Gleb Smirnoff <glebius@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r357293 - head/sys/net Message-ID: <1bd0ae2c-3b5a-dfd7-747b-75af6f8d4d03@selasky.org> In-Reply-To: <20200130205629.GK1268@FreeBSD.org> References: <202001301204.00UC43Rw022059@repo.freebsd.org> <20200130205629.GK1268@FreeBSD.org>
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On 2020-01-30 21:56, Gleb Smirnoff wrote: > On Thu, Jan 30, 2020 at 12:04:03PM +0000, Hans Petter Selasky wrote: > H> Author: hselasky > H> Date: Thu Jan 30 12:04:02 2020 > H> New Revision: 357293 > H> URL: https://svnweb.freebsd.org/changeset/base/357293 > H> > H> Log: > H> Widen EPOCH(9) usage in netisr. > H> > H> Software interrupt handlers are allowed to sleep. In swi_net() there > H> is a read lock behind NETISR_RLOCK() which in turn ends up calling > H> msleep() which means the whole of swi_net() cannot be protected by an > H> EPOCH(9) section. By default the NETISR_LOCKING feature is disabled. > H> > H> This issue was introduced by r357004. This is a preparation step for > H> replacing the functionality provided by r357004. > H> > H> Found by: kib@ > H> Sponsored by: Mellanox Technologies > > What?! NETISR_RLOCK() which in turn ends up calling msleep()? Can you please > explain this nonsense? > See rms_rlock_fallback() in kern_rmlock.c . --HPS
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