From: Mukul Joshi <mukul.joshi@xxxxxxx>
Currently, even if kfd_locked is set, a process is first
created and then removed to work around a race condition
in updating kfd_locked flag. Rework kfd_locked handling to
ensure no processes is created if kfd_locked is set. This
is achieved by updating kfd_locked under kfd_processes_mutex.
With this there is no need for kfd_locked to be an atomic
counter. Instead, it can be a regular integer.
Signed-off-by: Mukul Joshi <mukul.joshi@xxxxxxx>
Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
---
drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 7 -------
drivers/gpu/drm/amd/amdkfd/kfd_device.c | 21 ++++++++++++++++-----
drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 2 ++
drivers/gpu/drm/amd/amdkfd/kfd_process.c | 8 +++++++-
4 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index cf1a97583901..82749405be79 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -146,13 +146,6 @@ static int kfd_open(struct inode *inode, struct file *filep)
if (IS_ERR(process))
return PTR_ERR(process);
- if (kfd_is_locked()) {
- dev_dbg(kfd_device, "kfd is locked!\n"
- "process %d unreferenced", process->pasid);
- kfd_unref_process(process);
- return -EAGAIN;
- }
-
/* filep now owns the reference returned by kfd_create_process */
filep->private_data = process;
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
index 1a482f0855d2..7aa4f4ee7752 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
@@ -42,7 +42,7 @@
* once locked, kfd driver will stop any further GPU execution.
* create process (open) will return -EAGAIN.
*/
-static atomic_t kfd_locked = ATOMIC_INIT(0);
+static int kfd_locked;
#ifdef CONFIG_DRM_AMDGPU_CIK
extern const struct kfd2kgd_calls gfx_v7_kfd2kgd;
@@ -872,7 +872,9 @@ int kgd2kfd_post_reset(struct kfd_dev *kfd)
return ret;
}
- atomic_dec(&kfd_locked);
+ mutex_lock(&kfd_processes_mutex);
+ --kfd_locked;
+ mutex_unlock(&kfd_processes_mutex);
for (i = 0; i < kfd->num_nodes; i++) {
node = kfd->nodes[i];
@@ -885,21 +887,27 @@ int kgd2kfd_post_reset(struct kfd_dev *kfd)
bool kfd_is_locked(void)
{
- return (atomic_read(&kfd_locked) > 0);
+ lockdep_assert_held(&kfd_processes_mutex);
+ return (kfd_locked > 0);
}
void kgd2kfd_suspend(struct kfd_dev *kfd, bool run_pm)
{
struct kfd_node *node;
int i;
+ int count;
if (!kfd->init_complete)
return;
/* for runtime suspend, skip locking kfd */
if (!run_pm) {
+ mutex_lock(&kfd_processes_mutex);
+ count = ++kfd_locked;
+ mutex_unlock(&kfd_processes_mutex);
+
/* For first KFD device suspend all the KFD processes */
- if (atomic_inc_return(&kfd_locked) == 1)
+ if (count == 1)
kfd_suspend_all_processes();
}
@@ -925,7 +933,10 @@ int kgd2kfd_resume(struct kfd_dev *kfd, bool run_pm)
/* for runtime resume, skip unlocking kfd */
if (!run_pm) {
- count = atomic_dec_return(&kfd_locked);
+ mutex_lock(&kfd_processes_mutex);
+ count = --kfd_locked;
+ mutex_unlock(&kfd_processes_mutex);
+
WARN_ONCE(count < 0, "KFD suspend / resume ref. error");
if (count == 0)
ret = kfd_resume_all_processes();
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index 5cfebcc8b305..400b4dcbdf05 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -201,6 +201,8 @@ extern int amdgpu_no_queue_eviction_on_vm_fault;
/* Enable eviction debug messages */
extern bool debug_evictions;
+extern struct mutex kfd_processes_mutex;
+
enum cache_policy {
cache_policy_coherent,
cache_policy_noncoherent
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 9e667fa38df1..75cd4eafaa44 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -50,7 +50,7 @@ struct mm_struct;
* Unique/indexed by mm_struct*
*/
DEFINE_HASHTABLE(kfd_processes_table, KFD_PROCESS_TABLE_SIZE);
-static DEFINE_MUTEX(kfd_processes_mutex);
+DEFINE_MUTEX(kfd_processes_mutex);
DEFINE_SRCU(kfd_processes_srcu);
@@ -818,6 +818,12 @@ struct kfd_process *kfd_create_process(struct file *filep)
*/
mutex_lock(&kfd_processes_mutex);
+ if (kfd_is_locked()) {
+ mutex_unlock(&kfd_processes_mutex);
+ pr_debug("KFD is locked! Cannot create process");
+ return ERR_PTR(-EINVAL);
+ }
+
/* A prior open of /dev/kfd could have already created the process. */
process = find_process(thread, false);
if (process) {
--
2.39.2
