/* eBPF example program: * * - Creates arraymap in kernel with 4 bytes keys and 8 byte values * * - Loads eBPF program * * The eBPF program accesses the map passed in to store two pieces of * information. The number of invocations of the program, which maps * to the number of packets received, is stored to key 0. Key 1 is * incremented on each iteration by the number of bytes stored in * the skb. * * - Attaches the new program to a cgroup using BPF_PROG_ATTACH * * - Every second, reads map[0] and map[1] to see how many bytes and * packets were seen on any socket of tasks in the given cgroup. */ #define _GNU_SOURCE #include #include #include #include #include #include "libbpf.h" #include "cgroup_helpers.h" #define FOO "/foo" #define BAR "/foo/bar/" #define PING_CMD "ping -c1 -w1 127.0.0.1" char bpf_log_buf[BPF_LOG_BUF_SIZE]; static int prog_load(int verdict) { int ret; struct bpf_insn prog[] = { BPF_MOV64_IMM(BPF_REG_0, verdict), /* r0 = verdict */ BPF_EXIT_INSN(), }; size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn); ret = bpf_load_program(BPF_PROG_TYPE_CGROUP_SKB, prog, insns_cnt, "GPL", 0, bpf_log_buf, BPF_LOG_BUF_SIZE); if (ret < 0) { log_err("Loading program"); printf("Output from verifier:\n%s\n-------\n", bpf_log_buf); return 0; } return ret; } int main(int argc, char **argv) { int drop_prog, allow_prog, foo = 0, bar = 0, rc = 0; allow_prog = prog_load(1); if (!allow_prog) goto err; drop_prog = prog_load(0); if (!drop_prog) goto err; if (setup_cgroup_environment()) goto err; /* Create cgroup /foo, get fd, and join it */ foo = create_and_get_cgroup(FOO); if (!foo) goto err; if (join_cgroup(FOO)) goto err; if (bpf_prog_attach(drop_prog, foo, BPF_CGROUP_INET_EGRESS)) { log_err("Attaching prog to /foo"); goto err; } assert(system(PING_CMD) != 0); /* Create cgroup /foo/bar, get fd, and join it */ bar = create_and_get_cgroup(BAR); if (!bar) goto err; if (join_cgroup(BAR)) goto err; assert(system(PING_CMD) != 0); if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { log_err("Attaching prog to /foo/bar"); goto err; } assert(system(PING_CMD) == 0); if (bpf_prog_detach(bar, BPF_CGROUP_INET_EGRESS)) { log_err("Detaching program from /foo/bar"); goto err; } assert(system(PING_CMD) != 0); if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { log_err("Attaching prog to /foo/bar"); goto err; } if (bpf_prog_detach(foo, BPF_CGROUP_INET_EGRESS)) { log_err("Detaching program from /foo"); goto err; } assert(system(PING_CMD) == 0); goto out; err: rc = 1; out: close(foo); close(bar); cleanup_cgroup_environment(); return rc; } c321e4a1f31f98194e4f6b6cae7'>sound/core/memalloc.c
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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-30 19:27:10 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-31 09:13:49 -0500
commit79c6f448c8b79c321e4a1f31f98194e4f6b6cae7 (patch)
tree370efda701f03cccf21e02bb1fdd3b852547d75c /sound/core/memalloc.c
parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
tracing: Fix hwlat kthread migration
The hwlat tracer creates a kernel thread at start of the tracer. It is pinned to a single CPU and will move to the next CPU after each period of running. If the user modifies the migration thread's affinity, it will not change after that happens. The original code created the thread at the first instance it was called, but later was changed to destroy the thread after the tracer was finished, and would not be created until the next instance of the tracer was established. The code that initialized the affinity was only called on the initial instantiation of the tracer. After that, it was not initialized, and the previous affinity did not match the current newly created one, making it appear that the user modified the thread's affinity when it did not, and the thread failed to migrate again. Cc: stable@vger.kernel.org Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'sound/core/memalloc.c')