evie/android_kernel_oneplus_msm8998
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qseecom: fix a race condition when TA is blocked

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When the thread processing blocked TA wakes up when listener
becames available, the listener may be unavailable again before
this thread grabs the global mutex, so make change to add a
while loop to check if listener available after wake up and hold
mutex.

Change-Id: Ib386faca7a44325142da1dc54e19a99f3173ec86
Signed-off-by: Zhen Kong <zkong@codeaurora.org>
This commit is contained in:
Zhen Kong 2017-11-13 15:13:31 -08:00 • committed by Gerrit - the friendly Code Review server
parent 55cbbe6873
commit 69fb586ddb
1 changed files with 24 additions and 20 deletions
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44
drivers/misc/qseecom.c
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@ -1898,20 +1898,22 @@ static int __qseecom_process_blocked_on_listener_legacy(
ptr_app->blocked_on_listener_id = resp->data;
/* sleep until listener is available */
qseecom.app_block_ref_cnt++;
ptr_app->app_blocked = true;
mutex_unlock(&app_access_lock);
if (wait_event_freezable(
do {
qseecom.app_block_ref_cnt++;
ptr_app->app_blocked = true;
mutex_unlock(&app_access_lock);
if (wait_event_freezable(
list_ptr->listener_block_app_wq,
!list_ptr->listener_in_use)) {
pr_err("Interrupted: listener_id %d, app_id %d\n",
pr_err("Interrupted: listener_id %d, app_id %d\n",
resp->data, ptr_app->app_id);
ret = -ERESTARTSYS;
goto exit;
}
mutex_lock(&app_access_lock);
ptr_app->app_blocked = false;
qseecom.app_block_ref_cnt--;
ret = -ERESTARTSYS;
goto exit;
}
mutex_lock(&app_access_lock);
ptr_app->app_blocked = false;
qseecom.app_block_ref_cnt--;
} while (list_ptr->listener_in_use);
ptr_app->blocked_on_listener_id = 0;
/* notify the blocked app that listener is available */
@ -1962,18 +1964,20 @@ static int __qseecom_process_blocked_on_listener_smcinvoke(
pr_debug("lsntr %d in_use = %d\n",
resp->data, list_ptr->listener_in_use);
/* sleep until listener is available */
qseecom.app_block_ref_cnt++;
mutex_unlock(&app_access_lock);
if (wait_event_freezable(
do {
qseecom.app_block_ref_cnt++;
mutex_unlock(&app_access_lock);
if (wait_event_freezable(
list_ptr->listener_block_app_wq,
!list_ptr->listener_in_use)) {
pr_err("Interrupted: listener_id %d, session_id %d\n",
pr_err("Interrupted: listener_id %d, session_id %d\n",
resp->data, session_id);
ret = -ERESTARTSYS;
goto exit;
}
mutex_lock(&app_access_lock);
qseecom.app_block_ref_cnt--;
ret = -ERESTARTSYS;
goto exit;
}
mutex_lock(&app_access_lock);
qseecom.app_block_ref_cnt--;
} while (list_ptr->listener_in_use);
/* notify TZ that listener is available */
pr_warn("Lsntr %d is available, unblock session(%d) in TZ\n",