This patch annotates a few semi-random error paths in perf core to illustrate the extended error reporting facility. Most of them can be triggered from perf tools.
Signed-off-by: Alexander Shishkin <alexander.shish...@linux.intel.com> --- kernel/events/core.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 3ff28fc8bd..7beab37ea6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3382,10 +3382,10 @@ find_lively_task_by_vpid(pid_t vpid) rcu_read_unlock(); if (!task) - return ERR_PTR(-ESRCH); + return PERF_ERR_PTR(-ESRCH, "task not found"); /* Reuse ptrace permission checks for now. */ - err = -EACCES; + err = perf_err(-EACCES, "insufficient permissions for tracing this task"); if (!ptrace_may_access(task, PTRACE_MODE_READ)) goto errout; @@ -3413,7 +3413,8 @@ find_get_context(struct pmu *pmu, struct task_struct *task, if (!task) { /* Must be root to operate on a CPU event: */ if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) - return ERR_PTR(-EACCES); + return PERF_ERR_PTR(-EACCES, + "must be root to operate on a CPU event"); /* * We could be clever and allow to attach a event to an @@ -3421,7 +3422,7 @@ find_get_context(struct pmu *pmu, struct task_struct *task, * that's for later. */ if (!cpu_online(cpu)) - return ERR_PTR(-ENODEV); + return PERF_ERR_PTR(-ENODEV, "cpu is offline"); cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); ctx = &cpuctx->ctx; @@ -8134,15 +8135,16 @@ SYSCALL_DEFINE5(perf_event_open, if (!attr.exclude_kernel) { if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) - return -EACCES; + return perf_err_sync(&attr, -EACCES, + "kernel tracing forbidden for the unprivileged"); } if (attr.freq) { if (attr.sample_freq > sysctl_perf_event_sample_rate) - return -EINVAL; + return perf_err_sync(&attr, -EINVAL, "sample_freq too high"); } else { if (attr.sample_period & (1ULL << 63)) - return -EINVAL; + return perf_err_sync(&attr, -EINVAL, "sample_period too high"); } /* @@ -8152,14 +8154,14 @@ SYSCALL_DEFINE5(perf_event_open, * cgroup. */ if ((flags & PERF_FLAG_PID_CGROUP) && (pid == -1 || cpu == -1)) - return -EINVAL; + return perf_err_sync(&attr, -EINVAL, "pid and cpu need to be set in cgroup mode"); if (flags & PERF_FLAG_FD_CLOEXEC) f_flags |= O_CLOEXEC; event_fd = get_unused_fd_flags(f_flags); if (event_fd < 0) - return event_fd; + return perf_err_sync(&attr, event_fd, "can't obtain a file descriptor"); if (group_fd != -1) { err = perf_fget_light(group_fd, &group); -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/