From 38a81da2205f94e8a2a834b51a6b99c91fc7c2e8 Mon Sep 17 00:00:00 2001 From: Matt Helsley Date: Mon, 13 Sep 2010 13:01:20 -0700 Subject: [PATCH] perf events: Clean up pid passing The kernel perf event creation path shouldn't use find_task_by_vpid() because a vpid exists in a specific namespace. find_task_by_vpid() uses current's pid namespace which isn't always the correct namespace to use for the vpid in all the places perf_event_create_kernel_counter() (and thus find_get_context()) is called. The goal is to clean up pid namespace handling and prevent bugs like: https://bugzilla.kernel.org/show_bug.cgi?id=17281 Instead of using pids switch find_get_context() to use task struct pointers directly. The syscall is responsible for resolving the pid to a task struct. This moves the pid namespace resolution into the syscall much like every other syscall that takes pid parameters. Signed-off-by: Matt Helsley Signed-off-by: Peter Zijlstra Cc: Robin Green Cc: Prasad Cc: Arnaldo Carvalho de Melo Cc: Steven Rostedt Cc: Will Deacon Cc: Mahesh Salgaonkar LKML-Reference: Signed-off-by: Ingo Molnar --- arch/arm/oprofile/common.c | 2 +- include/linux/perf_event.h | 2 +- kernel/hw_breakpoint.c | 5 ++--- kernel/perf_event.c | 21 ++++++++++----------- kernel/watchdog.c | 2 +- 5 files changed, 15 insertions(+), 17 deletions(-) diff --git a/arch/arm/oprofile/common.c b/arch/arm/oprofile/common.c index 0691176899f..aad63e611b3 100644 --- a/arch/arm/oprofile/common.c +++ b/arch/arm/oprofile/common.c @@ -96,7 +96,7 @@ static int op_create_counter(int cpu, int event) return ret; pevent = perf_event_create_kernel_counter(&counter_config[event].attr, - cpu, -1, + cpu, NULL, op_overflow_handler); if (IS_ERR(pevent)) { diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 93bf53aa50e..39d8860b268 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -902,7 +902,7 @@ extern int perf_event_release_kernel(struct perf_event *event); extern struct perf_event * perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, - pid_t pid, + struct task_struct *task, perf_overflow_handler_t callback); extern u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running); diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c index 6122f02cfed..3b714e839c1 100644 --- a/kernel/hw_breakpoint.c +++ b/kernel/hw_breakpoint.c @@ -433,8 +433,7 @@ register_user_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, struct task_struct *tsk) { - return perf_event_create_kernel_counter(attr, -1, task_pid_vnr(tsk), - triggered); + return perf_event_create_kernel_counter(attr, -1, tsk, triggered); } EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); @@ -516,7 +515,7 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, get_online_cpus(); for_each_online_cpu(cpu) { pevent = per_cpu_ptr(cpu_events, cpu); - bp = perf_event_create_kernel_counter(attr, cpu, -1, triggered); + bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered); *pevent = bp; diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 3f5309db72f..86f394e15d5 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -2053,15 +2053,14 @@ errout: } static struct perf_event_context * -find_get_context(struct pmu *pmu, pid_t pid, int cpu) +find_get_context(struct pmu *pmu, struct task_struct *task, int cpu) { struct perf_event_context *ctx; struct perf_cpu_context *cpuctx; - struct task_struct *task; unsigned long flags; int ctxn, err; - if (pid == -1 && cpu != -1) { + if (!task && cpu != -1) { /* Must be root to operate on a CPU event: */ if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) return ERR_PTR(-EACCES); @@ -2084,10 +2083,6 @@ find_get_context(struct pmu *pmu, pid_t pid, int cpu) return ctx; } - task = find_lively_task_by_vpid(pid); - if (IS_ERR(task)) - return (void*)task; - err = -EINVAL; ctxn = pmu->task_ctx_nr; if (ctxn < 0) @@ -5527,6 +5522,7 @@ SYSCALL_DEFINE5(perf_event_open, struct perf_event_context *ctx; struct file *event_file = NULL; struct file *group_file = NULL; + struct task_struct *task = NULL; struct pmu *pmu; int event_fd; int fput_needed = 0; @@ -5581,10 +5577,13 @@ SYSCALL_DEFINE5(perf_event_open, if ((pmu->task_ctx_nr == perf_sw_context) && group_leader) pmu = group_leader->pmu; + if (pid != -1) + task = find_lively_task_by_vpid(pid); + /* * Get the target context (task or percpu): */ - ctx = find_get_context(pmu, pid, cpu); + ctx = find_get_context(pmu, task, cpu); if (IS_ERR(ctx)) { err = PTR_ERR(ctx); goto err_group_fd; @@ -5666,11 +5665,11 @@ err_fd: * * @attr: attributes of the counter to create * @cpu: cpu in which the counter is bound - * @pid: task to profile + * @task: task to profile (NULL for percpu) */ struct perf_event * perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, - pid_t pid, + struct task_struct *task, perf_overflow_handler_t overflow_handler) { struct perf_event_context *ctx; @@ -5687,7 +5686,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, goto err; } - ctx = find_get_context(event->pmu, pid, cpu); + ctx = find_get_context(event->pmu, task, cpu); if (IS_ERR(ctx)) { err = PTR_ERR(ctx); goto err_free; diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 89eadbb9cef..dc8e16824b5 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -358,7 +358,7 @@ static int watchdog_nmi_enable(int cpu) /* Try to register using hardware perf events */ wd_attr = &wd_hw_attr; wd_attr->sample_period = hw_nmi_get_sample_period(); - event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback); + event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback); if (!IS_ERR(event)) { printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n"); goto out_save; -- 2.39.3