From 27cdaa29f46fe6585f31bb4d315b3153d97dbd23 Mon Sep 17 00:00:00 2001
From: Philip Yang <Philip.Yang@amd.com>
Date: Mon, 24 Jan 2022 16:40:44 -0500
Subject: drm/amdkfd: Don't take process mutex for svm ioctls
Git-commit: ac7c48c0cce00d03b3c95fddcccb0a45257e33e3
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

SVM ioctls take proper svms->lock to handle race conditions, don't need
take process mutex to serialize ioctls. This also fixes circular locking
warning:

WARNING: possible circular locking dependency detected

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock((work_completion)(&svms->deferred_list_work));
                                lock(&process->mutex);
                     lock((work_completion)(&svms->deferred_list_work));
   lock(&process->mutex);

   *** DEADLOCK ***

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 26a593b3d7dc..214a2c67fba4 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1847,13 +1847,9 @@ static int kfd_ioctl_svm(struct file *filep, struct kfd_process *p, void *data)
 	if (!args->start_addr || !args->size)
 		return -EINVAL;
 
-	mutex_lock(&p->mutex);
-
 	r = svm_ioctl(p, args->op, args->start_addr, args->size, args->nattr,
 		      args->attrs);
 
-	mutex_unlock(&p->mutex);
-
 	return r;
 }
 #else
-- 
2.38.1