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[69.159.36.31]) by smtp.gmail.com with ESMTPSA id x23sm5092110iob.57.2019.05.13.17.24.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 13 May 2019 17:24:42 -0700 (PDT) Sender: Mark Johnston Date: Mon, 13 May 2019 20:24:37 -0400 From: Mark Johnston To: Li-Wen Hsu Cc: "Andrey V. Elsukov" , src-committers , svn-src-all@freebsd.org, svn-src-head@freebsd.org, melifaro@freebsd.org Subject: Re: svn commit: r347526 - head/sys/net Message-ID: <20190514002437.GA51157@raichu> References: <201905131345.x4DDjTRn092669@repo.freebsd.org> <20190513193754.GA37655@raichu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) X-Rspamd-Queue-Id: 4A7D174723 X-Spamd-Bar: ------ Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-6.99 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; REPLY(-4.00)[]; NEURAL_HAM_SHORT(-0.99)[-0.986,0] X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 14 May 2019 00:24:44 -0000 On Mon, May 13, 2019 at 06:09:59PM -0400, Li-Wen Hsu wrote: > On Mon, May 13, 2019 at 3:38 PM Mark Johnston wrote: > > > > On Mon, May 13, 2019 at 01:45:29PM +0000, Andrey V. Elsukov wrote: > > > Author: ae > > > Date: Mon May 13 13:45:28 2019 > > > New Revision: 347526 > > > URL: https://svnweb.freebsd.org/changeset/base/347526 > > > > > > Log: > > > Rework locking in BPF code to remove rwlock from fast path. > > > > > > On high packets rate the contention on rwlock in bpf_*tap*() functions > > > can lead to packets dropping. To avoid this, migrate this code to use > > > epoch(9) KPI and ConcurrencyKit's lists. > > > > > > * all lists changed to use CK_LIST; > > > * reference counting added to bpf_if and bpf_d; > > > * now bpf_if references ifnet and releases this reference on destroy; > > > * each bpf_d descriptor references bpf_if when it is attached; > > > * new struct bpf_program_buffer introduced to keep BPF filter programs; > > > * bpf_program_buffer, bpf_d and bpf_if structures are freed by > > > epoch_call(); > > > * bpf_freelist and ifnet_departure event are no longer needed, thus > > > both are removed; > > > > > > Reviewed by: melifaro > > > Sponsored by: Yandex LLC > > > Differential Revision: https://reviews.freebsd.org/D20224 > > > > This seems to introduce a possible recursion on the bpf cdev mutex. Now > > bpfwrite() holds the mutex over the if_output call, which may enter > > bpf_mtap() via bridge_transmit(), and bpf_mtap() may attempt to > > reacquire the mutex. > > It does, the sys.netinet.fibs_test.arpresolve_checks_interface_fib > case can trigger a panic: > > root@:/usr/tests/sys/netinet # kyua test > fibs_test:arpresolve_checks_interface_fib > fibs_test:arpresolve_checks_interface_fib -> panic: _mtx_lock_sleep: > recursed on non-recursive mutex bpf @ /usr/src/sys/net/bpf.c:2325 The problem should be fixed by r347549.