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From:   KeMeng Shi <shikemeng@huawei.com>
To:     <akpm@linux-foundation.org>, <james.morris@microsoft.com>,
        <gregkh@linuxfoundation.org>, <mortonm@chromium.org>,
        <will.deacon@arm.com>, <kristina.martsenko@arm.com>,
        <yuehaibing@huawei.com>, <malat@debian.org>,
        <j.neuschaefer@gmx.net>
CC:     <linux-kernel@vger.kernel.org>
Subject: [PATCH] connector: report comm change event when modifying /proc/pid/task/tid/comm
Date:   Mon, 16 Sep 2019 10:13:41 -0400
Message-ID: <20190916141341.658-1-shikemeng@huawei.com>
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Commit f786ecba41588 ("connector: add comm change event report to proc
 connector") added proc_comm_connector to report comm change event, and
prctl will report comm change event when dealing with PR_SET_NAME case.

prctl can only set the name of the calling thread. In order to set the name
of other threads in a process, modifying /proc/self/task/tid/comm is a
general way.It's exactly how pthread_setname_np do to set name of a thread.

It's unable to get comm change event of thread if the name of thread is set
by other thread via pthread_setname_np. This update provides a chance for
application to monitor and control threads whose name is set by other
threads.

Signed-off-by: KeMeng Shi <shikemeng@huawei.com>
---
 fs/proc/base.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index ebea9501afb8..34ffe572ac69 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -94,6 +94,7 @@
 #include <linux/sched/debug.h>
 #include <linux/sched/stat.h>
 #include <linux/posix-timers.h>
+#include <linux/cn_proc.h>
 #include <trace/events/oom.h>
 #include "internal.h"
 #include "fd.h"
@@ -1549,10 +1550,12 @@ static ssize_t comm_write(struct file *file, const char __user *buf,
 	if (!p)
 		return -ESRCH;
 
-	if (same_thread_group(current, p))
+	if (same_thread_group(current, p)) {
 		set_task_comm(p, buffer);
-	else
+		proc_comm_connector(p);
+	} else {
 		count = -EINVAL;
+	}
 
 	put_task_struct(p);
 
-- 
2.19.1