[PATCH 4/5] habanalabs: add a lock to protect multiple reset variables

From: Oded Gabbay
Date: Sun Dec 26 2021 - 07:43:20 EST

Next message: Oded Gabbay: "[PATCH 5/5] habanalabs: support hard-reset scheduling during soft-reset"
Previous message: Oded Gabbay: "[PATCH 2/5] habanalabs: handle skip multi-CS if handling not done"
In reply to: Oded Gabbay: "[PATCH 2/5] habanalabs: handle skip multi-CS if handling not done"
Next in thread: Oded Gabbay: "[PATCH 5/5] habanalabs: support hard-reset scheduling during soft-reset"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

From: Ofir Bitton <obitton@xxxxxxxxx>

Atomic operations during reset are replaced by a spinlock in order
to have the ability to protect more than a single variable.

Signed-off-by: Ofir Bitton <obitton@xxxxxxxxx>
Reviewed-by: Oded Gabbay <ogabbay@xxxxxxxxxx>
Signed-off-by: Oded Gabbay <ogabbay@xxxxxxxxxx>
---
.../misc/habanalabs/common/command_buffer.c | 3 +-
drivers/misc/habanalabs/common/debugfs.c | 16 +++---
drivers/misc/habanalabs/common/device.c | 50 +++++++++++++------
drivers/misc/habanalabs/common/habanalabs.h | 6 ++-
4 files changed, 49 insertions(+), 26 deletions(-)

diff --git a/drivers/misc/habanalabs/common/command_buffer.c b/drivers/misc/habanalabs/common/command_buffer.c
index 649380bb189f..3c0ae07a2d80 100644
--- a/drivers/misc/habanalabs/common/command_buffer.c
+++ b/drivers/misc/habanalabs/common/command_buffer.c
@@ -250,8 +250,7 @@ int hl_cb_create(struct hl_device *hdev, struct hl_cb_mgr *mgr,
* Can't use generic function to check this because of special case
* where we create a CB as part of the reset process
*/
- if ((hdev->disabled) || ((atomic_read(&hdev->reset_info.in_reset)) &&
- (ctx_id != HL_KERNEL_ASID_ID))) {
+ if ((hdev->disabled) || (hdev->reset_info.in_reset && (ctx_id != HL_KERNEL_ASID_ID))) {
dev_warn_ratelimited(hdev->dev,
"Device is disabled or in reset. Can't create new CBs\n");
rc = -EBUSY;
diff --git a/drivers/misc/habanalabs/common/debugfs.c b/drivers/misc/habanalabs/common/debugfs.c
index 746d1a18de63..fc084ee5106e 100644
--- a/drivers/misc/habanalabs/common/debugfs.c
+++ b/drivers/misc/habanalabs/common/debugfs.c
@@ -527,7 +527,7 @@ static int engines_show(struct seq_file *s, void *data)
struct hl_dbg_device_entry *dev_entry = entry->dev_entry;
struct hl_device *hdev = dev_entry->hdev;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev,
"Can't check device idle during reset\n");
return 0;
@@ -658,7 +658,7 @@ static ssize_t hl_data_read32(struct file *f, char __user *buf,
ssize_t rc;
u32 val;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev, "Can't read during reset\n");
return 0;
}
@@ -694,7 +694,7 @@ static ssize_t hl_data_write32(struct file *f, const char __user *buf,
u32 value;
ssize_t rc;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev, "Can't write during reset\n");
return 0;
}
@@ -731,7 +731,7 @@ static ssize_t hl_data_read64(struct file *f, char __user *buf,
ssize_t rc;
u64 val;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev, "Can't read during reset\n");
return 0;
}
@@ -767,7 +767,7 @@ static ssize_t hl_data_write64(struct file *f, const char __user *buf,
u64 value;
ssize_t rc;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev, "Can't write during reset\n");
return 0;
}
@@ -802,7 +802,7 @@ static ssize_t hl_dma_size_write(struct file *f, const char __user *buf,
ssize_t rc;
u32 size;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev, "Can't DMA during reset\n");
return 0;
}
@@ -1077,7 +1077,7 @@ static ssize_t hl_clk_gate_write(struct file *f, const char __user *buf,
u64 value;
ssize_t rc;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev,
"Can't change clock gating during reset\n");
return 0;
@@ -1119,7 +1119,7 @@ static ssize_t hl_stop_on_err_write(struct file *f, const char __user *buf,
u32 value;
ssize_t rc;

- if (atomic_read(&hdev->reset_info.in_reset)) {
+ if (hdev->reset_info.in_reset) {
dev_warn_ratelimited(hdev->dev,
"Can't change stop on error during reset\n");
return 0;
diff --git a/drivers/misc/habanalabs/common/device.c b/drivers/misc/habanalabs/common/device.c
index f8f9eb7a934f..84621ad765bc 100644
--- a/drivers/misc/habanalabs/common/device.c
+++ b/drivers/misc/habanalabs/common/device.c
@@ -17,7 +17,7 @@ enum hl_device_status hl_device_status(struct hl_device *hdev)
{
enum hl_device_status status;

- if (atomic_read(&hdev->reset_info.in_reset))
+ if (hdev->reset_info.in_reset)
status = HL_DEVICE_STATUS_IN_RESET;
else if (hdev->reset_info.needs_reset)
status = HL_DEVICE_STATUS_NEEDS_RESET;
@@ -448,11 +448,11 @@ static int device_early_init(struct hl_device *hdev)
mutex_init(&hdev->debug_lock);
INIT_LIST_HEAD(&hdev->cs_mirror_list);
spin_lock_init(&hdev->cs_mirror_lock);
+ spin_lock_init(&hdev->reset_info.lock);
INIT_LIST_HEAD(&hdev->fpriv_list);
INIT_LIST_HEAD(&hdev->fpriv_ctrl_list);
mutex_init(&hdev->fpriv_list_lock);
mutex_init(&hdev->fpriv_ctrl_list_lock);
- atomic_set(&hdev->reset_info.in_reset, 0);
mutex_init(&hdev->clk_throttling.lock);

return 0;
@@ -544,7 +544,7 @@ static void hl_device_heartbeat(struct work_struct *work)
* status for at least one heartbeat. From this point driver restarts
* tracking future consecutive fatal errors.
*/
- if (!(atomic_read(&hdev->reset_info.in_reset)))
+ if (!hdev->reset_info.in_reset)
hdev->reset_info.prev_reset_trigger = HL_RESET_TRIGGER_DEFAULT;

schedule_delayed_work(&hdev->work_heartbeat,
@@ -722,11 +722,14 @@ int hl_device_suspend(struct hl_device *hdev)
pci_save_state(hdev->pdev);

/* Block future CS/VM/JOB completion operations */
- rc = atomic_cmpxchg(&hdev->reset_info.in_reset, 0, 1);
- if (rc) {
+ spin_lock(&hdev->reset_info.lock);
+ if (hdev->reset_info.in_reset) {
+ spin_unlock(&hdev->reset_info.lock);
dev_err(hdev->dev, "Can't suspend while in reset\n");
return -EIO;
}
+ hdev->reset_info.in_reset = 1;
+ spin_unlock(&hdev->reset_info.lock);

/* This blocks all other stuff that is not blocked by in_reset */
hdev->disabled = true;
@@ -776,8 +779,10 @@ int hl_device_resume(struct hl_device *hdev)
}

- hdev->disabled = false;
- atomic_set(&hdev->reset_info.in_reset, 0);
+ /* 'in_reset' was set to true during suspend, now we must clear it in order
+ * for hard reset to be performed
+ */
+ hdev->reset_info.in_reset = 0;

rc = hl_device_reset(hdev, HL_DRV_RESET_HARD);
if (rc) {
@@ -1024,9 +1029,13 @@ int hl_device_reset(struct hl_device *hdev, u32 flags)
*/
if (!from_hard_reset_thread) {
/* Block future CS/VM/JOB completion operations */
- rc = atomic_cmpxchg(&hdev->reset_info.in_reset, 0, 1);
- if (rc)
+ spin_lock(&hdev->reset_info.lock);
+ if (hdev->reset_info.in_reset) {
+ spin_unlock(&hdev->reset_info.lock);
return 0;
+ }
+ hdev->reset_info.in_reset = 1;
+ spin_unlock(&hdev->reset_info.lock);

handle_reset_trigger(hdev, flags);

@@ -1234,7 +1243,7 @@ int hl_device_reset(struct hl_device *hdev, u32 flags)
}
}

- atomic_set(&hdev->reset_info.in_reset, 0);
+ hdev->reset_info.in_reset = 0;
hdev->reset_info.needs_reset = false;

dev_notice(hdev->dev, "Successfully finished resetting the device\n");
@@ -1272,7 +1281,7 @@ int hl_device_reset(struct hl_device *hdev, u32 flags)
goto again;
}

- atomic_set(&hdev->reset_info.in_reset, 0);
+ hdev->reset_info.in_reset = 0;

return rc;
}
@@ -1583,6 +1592,7 @@ int hl_device_init(struct hl_device *hdev, struct class *hclass)
*/
void hl_device_fini(struct hl_device *hdev)
{
+ bool device_in_reset;
ktime_t timeout;
u64 reset_sec;
int i, rc;
@@ -1606,10 +1616,22 @@ void hl_device_fini(struct hl_device *hdev)
*/

timeout = ktime_add_us(ktime_get(), reset_sec * 1000 * 1000);
- rc = atomic_cmpxchg(&hdev->reset_info.in_reset, 0, 1);
- while (rc) {
+
+ spin_lock(&hdev->reset_info.lock);
+ device_in_reset = !!hdev->reset_info.in_reset;
+ if (!device_in_reset)
+ hdev->reset_info.in_reset = 1;
+ spin_unlock(&hdev->reset_info.lock);
+
+ while (device_in_reset) {
usleep_range(50, 200);
- rc = atomic_cmpxchg(&hdev->reset_info.in_reset, 0, 1);
+
+ spin_lock(&hdev->reset_info.lock);
+ device_in_reset = !!hdev->reset_info.in_reset;
+ if (!device_in_reset)
+ hdev->reset_info.in_reset = 1;
+ spin_unlock(&hdev->reset_info.lock);
+
if (ktime_compare(ktime_get(), timeout) > 0) {
dev_crit(hdev->dev,
"Failed to remove device because reset function did not finish\n");
diff --git a/drivers/misc/habanalabs/common/habanalabs.h b/drivers/misc/habanalabs/common/habanalabs.h
index 47eaeff9e924..37a3a469b42f 100644
--- a/drivers/misc/habanalabs/common/habanalabs.h
+++ b/drivers/misc/habanalabs/common/habanalabs.h
@@ -2457,9 +2457,10 @@ struct last_error_session_info {

/**
* struct hl_reset_info - holds current device reset information.
- * @in_reset: is device in reset flow.
+ * @lock: lock to protect critical reset flows.
* @soft_reset_cnt: number of soft reset since the driver was loaded.
* @hard_reset_cnt: number of hard reset since the driver was loaded.
+ * @in_reset: is device in reset flow.
* @is_in_soft_reset: Device is currently in soft reset process.
* @needs_reset: true if reset_on_lockup is false and device should be reset
* due to lockup.
@@ -2474,9 +2475,10 @@ struct last_error_session_info {
* complete instead.
*/
struct hl_reset_info {
- atomic_t in_reset;
+ spinlock_t lock;
u32 soft_reset_cnt;
u32 hard_reset_cnt;
+ u8 in_reset;
u8 is_in_soft_reset;
u8 needs_reset;
u8 hard_reset_pending;
--
2.25.1

Next message: Oded Gabbay: "[PATCH 5/5] habanalabs: support hard-reset scheduling during soft-reset"
Previous message: Oded Gabbay: "[PATCH 2/5] habanalabs: handle skip multi-CS if handling not done"
In reply to: Oded Gabbay: "[PATCH 2/5] habanalabs: handle skip multi-CS if handling not done"
Next in thread: Oded Gabbay: "[PATCH 5/5] habanalabs: support hard-reset scheduling during soft-reset"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]