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drm/amdkfd: Rework kfd_locked handling

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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@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Mukul Joshi
2022-05-31 14:39:36 -04:00
committed by Alex Deucher
parent 6b22ef2574
commit fe1f05df59
4 changed files with 25 additions and 13 deletions
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7
drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
View File

@@ -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;

21
drivers/gpu/drm/amd/amdkfd/kfd_device.c
View File

@@ -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;
@@ -880,7 +880,9 @@ 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];
@@ -893,21 +895,27 @@ 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();
}
@@ -933,7 +941,10 @@ 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();

2
drivers/gpu/drm/amd/amdkfd/kfd_priv.h
View File

@@ -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

8
drivers/gpu/drm/amd/amdkfd/kfd_process.c
View File

@@ -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) {