Split out the code which searches for non-exiting tasks into its own
helper. Creating this helper not only makes the code slightly more
readable it prepares to move the search out of find_get_context() in
a subsequent commit.
Cc: Robin Green <greenrd@xxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: containers@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
---
kernel/perf_event.c | 63 ++++++++++++++++++++++++++++++++------------------
1 files changed, 40 insertions(+), 23 deletions(-)
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 440f9ca..3f5309d 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2015,6 +2015,43 @@ alloc_perf_context(struct pmu *pmu, struct task_struct *task)
return ctx;
}
+static struct task_struct *
+find_lively_task_by_vpid(pid_t vpid)
+{
+ struct task_struct *task;
+ int err;
+
+ rcu_read_lock();
+ if (!vpid)
+ task = current;
+ else
+ task = find_task_by_vpid(vpid);
+ if (task)
+ get_task_struct(task);
+ rcu_read_unlock();
+
+ if (!task)
+ return ERR_PTR(-ESRCH);
+
+ /*
+ * Can't attach events to a dying task.
+ */
+ err = -ESRCH;
+ if (task->flags & PF_EXITING)
+ goto errout;
+
+ /* Reuse ptrace permission checks for now. */
+ err = -EACCES;
+ if (!ptrace_may_access(task, PTRACE_MODE_READ))
+ goto errout;
+
+ return task;
+errout:
+ put_task_struct(task);
+ return ERR_PTR(err);
+
+}
+
static struct perf_event_context *
find_get_context(struct pmu *pmu, pid_t pid, int cpu)
{
@@ -2047,29 +2084,9 @@ find_get_context(struct pmu *pmu, pid_t pid, int cpu)
return ctx;
}
- rcu_read_lock();
- if (!pid)
- task = current;
- else
- task = find_task_by_vpid(pid);
- if (task)
- get_task_struct(task);
- rcu_read_unlock();
-
- if (!task)
- return ERR_PTR(-ESRCH);
-
- /*
- * Can't attach events to a dying task.
- */
- err = -ESRCH;
- if (task->flags & PF_EXITING)
- goto errout;
-
- /* Reuse ptrace permission checks for now. */
- err = -EACCES;
- if (!ptrace_may_access(task, PTRACE_MODE_READ))
- goto errout;
+ task = find_lively_task_by_vpid(pid);
+ if (IS_ERR(task))
+ return (void*)task;
err = -EINVAL;
ctxn = pmu->task_ctx_nr;
--
1.6.3.3
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