[PATCH] cxl: Fix struct pid leak when attaching a process through user API

[Frederic Barrat]

When the cxl driver creates a context, it stores the pid of the
calling task, and mistakenly increments the reference count of the
struct pid twice, once through get_task_pid(), once through
get_pid(). The reference count is only decremented once on detach. As
a result, a struct pid is leaked and it reduces the number of
processes that can run simultaneously by one.
The fix is to simply remove the call to get_pid().

There is a separate patch for the kernel API, since it goes to
different kernel versions.

Signed-off-by: Frederic Barrat <fbarrat at linux.vnet.ibm.com>
Cc: <stable at vger.kernel.org> # 3.18+
---
 drivers/misc/cxl/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index 7ccd299..97003ee 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -199,7 +199,7 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
 	 * behalf of another process, so the AFU's mm gets bound to the process
 	 * that performs this ioctl and not the process that opened the file.
 	 */
-	ctx->pid = get_pid(get_task_pid(current, PIDTYPE_PID));
+	ctx->pid = get_task_pid(current, PIDTYPE_PID);
 
 	trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr);
 
-- 
1.9.1