Commit 4ddf0a97 authored by Yu Liao's avatar Yu Liao
Browse files

cpuinspect: make inspector unregister reliable 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAO4PE


CVE: NA

----------------------------------------

Calling cpuinspect_unregister_inspector() while the inspector is running
will lead a issue as follow:

  [ 733.650856] Unable to handle kernel paging request at virtual address ffff80000922b0e4
  [ 733.651118] Call trace:
  [ 733.651136] run_inspector+0xe4/0x220 [cpu_inspect]
  [ 733.651148] kthread+0x108/0x150
  [ 733.651154] ret_from_fork+0x10/0x18

Return -EBUSY do not prevent the inspector form being removed. Fix this
by providing a synchronized stop function to ensure inspect threads are
really finished.

Fixes: 069486b6 ("cpuinspect: add CPU-inspect infrastructure")
Signed-off-by: default avatarYu Liao <liaoyu15@huawei.com>
parent 02994a9b

drivers/cpuinspect/cpuinspect.c

+14 −0
Original line number Diff line number Diff line
@@ -149,6 +149,20 @@ int stop_inspect_threads(void) 
	return 0;

}



/**

 * stop_inspect_threads_sync - Stop all the inspect threads and wait for

 * current inspect tasks to finish.

 *

 * This function must be called with the cpuinspect lock held.

 */

void stop_inspect_threads_sync(void)

{

	stop_inspect_threads();



	while (atomic_read(&active_threads_num))

		cpu_relax();

}



/**

 * cpuinspect_init - core initializer

 */

drivers/cpuinspect/cpuinspect.h

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ void cpuinspect_result_notify(void); 
/* inspect control */

int start_inspect_threads(void);

int stop_inspect_threads(void);

void stop_inspect_threads_sync(void);

int cpuinspect_is_running(void);



/* switch inspector */

drivers/cpuinspect/inspector.c

+1 −4
Original line number Diff line number Diff line
@@ -106,10 +106,7 @@ int cpuinspect_unregister_inspector(struct cpu_inspector *insp) 


	mutex_lock(&cpuinspect_lock);

	if (curr_cpu_inspector == insp) {

		if (ci_core.inspect_on) {

			mutex_unlock(&cpuinspect_lock);

			return -EBUSY;

		}

		stop_inspect_threads_sync();



		curr_cpu_inspector = NULL;

	}