/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com * Copyright (c) 2015 BMW Car IT GmbH * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */ #include #include #include #include "bpf_helpers.h" #define MAX_ENTRIES 20 #define MAX_CPU 4 /* We need to stick to static allocated memory (an array instead of * hash table) because managing dynamic memory from the * trace_preempt_[on|off] tracepoints hooks is not supported. */ struct bpf_map_def SEC("maps") my_map = { .type = BPF_MAP_TYPE_ARRAY, .key_size = sizeof(int), .value_size = sizeof(u64), .max_entries = MAX_CPU, }; SEC("kprobe/trace_preempt_off") int bpf_prog1(struct pt_regs *ctx) { int cpu = bpf_get_smp_processor_id(); u64 *ts = bpf_map_lookup_elem(&my_map, &cpu); if (ts) *ts = bpf_ktime_get_ns(); return 0; } static unsigned int log2(unsigned int v) { unsigned int r; unsigned int shift; r = (v > 0xFFFF) << 4; v >>= r; shift = (v > 0xFF) << 3; v >>= shift; r |= shift; shift = (v > 0xF) << 2; v >>= shift; r |= shift; shift = (v > 0x3) << 1; v >>= shift; r |= shift; r |= (v >> 1); return r; } static unsigned int log2l(unsigned long v) { unsigned int hi = v >> 32; if (hi) return log2(hi) + 32; else return log2(v); } struct bpf_map_def SEC("maps") my_lat = { .type = BPF_MAP_TYPE_ARRAY, .key_size = sizeof(int), .value_size = sizeof(long), .max_entries = MAX_CPU * MAX_ENTRIES, }; SEC("kprobe/trace_preempt_on") int bpf_prog2(struct pt_regs *ctx) { u64 *ts, cur_ts, delta; int key, cpu; long *val; cpu = bpf_get_smp_processor_id(); ts = bpf_map_lookup_elem(&my_map, &cpu); if (!ts) return 0; cur_ts = bpf_ktime_get_ns(); delta = log2l(cur_ts - *ts); if (delta > MAX_ENTRIES - 1) delta = MAX_ENTRIES - 1; key = cpu * MAX_ENTRIES + delta; val = bpf_map_lookup_elem(&my_lat, &key); if (val) __sync_fetch_and_add((long *)val, 1); return 0; } char _license[] SEC("license") = "GPL"; u32 _version SEC("version") = LINUX_VERSION_CODE; git.cgi/linux/net-next.git/log/net/core/net-sysfs.h'>
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authorAndrei Vagin <avagin@openvz.org>2017-01-04 19:28:14 -0800
committerEric W. Biederman <ebiederm@xmission.com>2017-01-10 13:34:56 +1300
commitadd7c65ca426b7a37184dd3d2172394e23d585d6 (patch)
tree28b08b519540041b06ed0ab0b1c005076b932e8e /net/core/net-sysfs.h
parent75422726b0f717d67db3283c2eb5bc14fa2619c5 (diff)
pid: fix lockdep deadlock warning due to ucount_lock
========================================================= [ INFO: possible irq lock inversion dependency detected ] 4.10.0-rc2-00024-g4aecec9-dirty #118 Tainted: G W --------------------------------------------------------- swapper/1/0 just changed the state of lock: (&(&sighand->siglock)->rlock){-.....}, at: [<ffffffffbd0a1bc6>] __lock_task_sighand+0xb6/0x2c0 but this lock took another, HARDIRQ-unsafe lock in the past: (ucounts_lock){+.+...} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &(&sighand->siglock)->rlock --> &(&tty->ctrl_lock)->rlock --> ucounts_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ucounts_lock); local_irq_disable(); lock(&(&sighand->siglock)->rlock); lock(&(&tty->ctrl_lock)->rlock); <Interrupt> lock(&(&sighand->siglock)->rlock); *** DEADLOCK *** This patch removes a dependency between rlock and ucount_lock. Fixes: f333c700c610 ("pidns: Add a limit on the number of pid namespaces") Cc: stable@vger.kernel.org Signed-off-by: Andrei Vagin <avagin@openvz.org> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'net/core/net-sysfs.h')