diff options
| author | Matt Helsley <matthltc@us.ibm.com> | 2010-09-13 13:01:20 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-09-15 10:44:00 +0200 |
| commit | 38a81da2205f94e8a2a834b51a6b99c91fc7c2e8 (patch) | |
| tree | 5227c665f37d1c472608a44aaad0a04be68befb2 /kernel/perf_event.c | |
| parent | 2ebd4ffb6d0cb877787b1e42be8485820158857e (diff) | |
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 <matthltc@us.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robin Green <greenrd@greenrd.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
LKML-Reference: <a134e5e392ab0204961fd1a62c84a222bf5874a9.1284407763.git.matthltc@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
| -rw-r--r-- | kernel/perf_event.c | 21 |
1 files changed, 10 insertions, 11 deletions
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; |