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Subject[RFC][PATCH 1/7] perf: Fix task refcount issues
Currently it looks like find_lively_task_by_vpid() takes a task ref
and relies on find_get_context() to drop it.

The problem is that perf_event_create_kernel_counter() shouldn't be
dropping task refs.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
---
kernel/perf_event.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -2124,11 +2124,9 @@ find_get_context(struct pmu *pmu, struct
}
}

- put_task_struct(task);
return ctx;

errout:
- put_task_struct(task);
return ERR_PTR(err);
}

@@ -5536,7 +5534,7 @@ SYSCALL_DEFINE5(perf_event_open,
ctx = find_get_context(pmu, task, cpu);
if (IS_ERR(ctx)) {
err = PTR_ERR(ctx);
- goto err_group_fd;
+ goto err_task;
}

/*
@@ -5632,6 +5630,9 @@ SYSCALL_DEFINE5(perf_event_open,

err_context:
put_ctx(ctx);
+err_task:
+ if (task)
+ put_task_struct(task);
err_group_fd:
fput_light(group_file, fput_needed);
free_event(event);



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