Commit 95b8aa9b authored Jul 14, 2017 by Zhen Kong

firmware: qcom: tz_log: change to use debugfs_create_file_unsafe

In the 4.9 kernel, a global srcu lock was added to debugfs file
operation, which will be hold during full_proxy_read operation. As
tz_log reading operation will sleep until there is new data coming,
this makes srcu deadlock with other driver debugfs operations. To
break deadlock for sleep use cases during debugfs_read, change to
use debugfs_create_file_unsafe(), then full_proxy_read is not used,
and it will not hold srcu lock. Besides, tz_log debugfs won't get
removed and thus, there is no need to protect it against removal
races. The use of debugfs_create_file_unsafe() is safe here.

Change-Id: I63efc408f4adb04a664c0944b899946770d60b18
Signed-off-by: Zhen Kong <zkong@codeaurora.org>

parent 7529b53b

drivers/firmware/qcom/tz_log.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -962,7 +962,7 @@ static int tzdbgfs_init(struct platform_device *pdev)

		for (i = 0; i < TZDBG_STATS_MAX; i++) {
		tzdbg.debug_tz[i] = i;
		dent = debugfs_create_file(tzdbg.stat[i].name,
		dent = debugfs_create_file_unsafe(tzdbg.stat[i].name,
		0444, dent_dir,
		&tzdbg.debug_tz[i], &tzdbg_fops);
		if (dent == NULL) {