Date: Mon, 3 Aug 2015 22:14:45 +0000 (UTC) From: Luiz Otavio O Souza <loos@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r286260 - head/sys/net Message-ID: <201508032214.t73MEjW1038794@repo.freebsd.org>
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Author: loos Date: Mon Aug 3 22:14:45 2015 New Revision: 286260 URL: https://svnweb.freebsd.org/changeset/base/286260 Log: Remove the mtx_sleep() from the kqueue f_event filter. The filter is called from the network hot path and must not sleep. The filter runs with the descriptor lock held and does not manipulates the buffers, so it is not necessary sleep when the hold buffer is in use. Just ignore the hold buffer contents when it is being copied to user space (when hold buffer in use is set). This fix the "Sleeping thread owns a non-sleepable lock" panic when the userland thread is too busy reading the packets from bpf(4). PR: 200323 MFC after: 2 weeks Sponsored by: Rubicon Communications (Netgate) Modified: head/sys/net/bpf.c Modified: head/sys/net/bpf.c ============================================================================== --- head/sys/net/bpf.c Mon Aug 3 22:07:50 2015 (r286259) +++ head/sys/net/bpf.c Mon Aug 3 22:14:45 2015 (r286260) @@ -2035,10 +2035,10 @@ filt_bpfread(struct knote *kn, long hint ready = bpf_ready(d); if (ready) { kn->kn_data = d->bd_slen; - while (d->bd_hbuf_in_use) - mtx_sleep(&d->bd_hbuf_in_use, &d->bd_lock, - PRINET, "bd_hbuf", 0); - if (d->bd_hbuf) + /* + * Ignore the hold buffer if it is being copied to user space. + */ + if (!d->bd_hbuf_in_use && d->bd_hbuf) kn->kn_data += d->bd_hlen; } else if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) { callout_reset(&d->bd_callout, d->bd_rtout,
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