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perf events: Split out task search into helper

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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.

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: <561205417b450b8a4bf7488374541d64b4690431.1284407762.git.matthltc@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Matt Helsley 2010-09-13 13:01:19 -07:00 committed by Ingo Molnar
parent d958077d00
commit 2ebd4ffb6d
1 changed files with 40 additions and 23 deletions
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63
kernel/perf_event.c
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@ -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;