6.8-stable review patch. If anyone has any objections, please let me know.
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From: Rex Zhang rex.zhang@intel.com
[ Upstream commit d5638de827cff0fce77007e426ec0ffdedf68a44 ]
drain_workqueue() cannot be called safely in a spinlocked context due to possible task rescheduling. In the multi-task scenario, calling queue_work() while drain_workqueue() will lead to a Call Trace as pushing a work on a draining workqueue is not permitted in spinlocked context. Call Trace: <TASK> ? __warn+0x7d/0x140 ? __queue_work+0x2b2/0x440 ? report_bug+0x1f8/0x200 ? handle_bug+0x3c/0x70 ? exc_invalid_op+0x18/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? __queue_work+0x2b2/0x440 queue_work_on+0x28/0x30 idxd_misc_thread+0x303/0x5a0 [idxd] ? __schedule+0x369/0xb40 ? __pfx_irq_thread_fn+0x10/0x10 ? irq_thread+0xbc/0x1b0 irq_thread_fn+0x21/0x70 irq_thread+0x102/0x1b0 ? preempt_count_add+0x74/0xa0 ? __pfx_irq_thread_dtor+0x10/0x10 ? __pfx_irq_thread+0x10/0x10 kthread+0x103/0x140 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK>
The current implementation uses a spinlock to protect event log workqueue and will lead to the Call Trace due to potential task rescheduling.
To address the locking issue, convert the spinlock to mutex, allowing the drain_workqueue() to be called in a safe mutex-locked context.
This change ensures proper synchronization when accessing the event log workqueue, preventing potential Call Trace and improving the overall robustness of the code.
Fixes: c40bd7d9737b ("dmaengine: idxd: process user page faults for completion record") Signed-off-by: Rex Zhang rex.zhang@intel.com Reviewed-by: Dave Jiang dave.jiang@intel.com Reviewed-by: Fenghua Yu fenghua.yu@intel.com Reviewed-by: Lijun Pan lijun.pan@intel.com Link: https://lore.kernel.org/r/20240404223949.2885604-1-fenghua.yu@intel.com Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/idxd/cdev.c | 5 ++--- drivers/dma/idxd/debugfs.c | 4 ++-- drivers/dma/idxd/device.c | 8 ++++---- drivers/dma/idxd/idxd.h | 2 +- drivers/dma/idxd/init.c | 2 +- drivers/dma/idxd/irq.c | 4 ++-- 6 files changed, 12 insertions(+), 13 deletions(-)
diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c index e5a94a93a3cc4..59456f21778b4 100644 --- a/drivers/dma/idxd/cdev.c +++ b/drivers/dma/idxd/cdev.c @@ -342,7 +342,7 @@ static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid) if (!evl) return;
- spin_lock(&evl->lock); + mutex_lock(&evl->lock); status.bits = ioread64(idxd->reg_base + IDXD_EVLSTATUS_OFFSET); t = status.tail; h = status.head; @@ -354,9 +354,8 @@ static void idxd_cdev_evl_drain_pasid(struct idxd_wq *wq, u32 pasid) set_bit(h, evl->bmap); h = (h + 1) % size; } - spin_unlock(&evl->lock); - drain_workqueue(wq->wq); + mutex_unlock(&evl->lock); }
static int idxd_cdev_release(struct inode *node, struct file *filep) diff --git a/drivers/dma/idxd/debugfs.c b/drivers/dma/idxd/debugfs.c index f3f25ee676f30..ad4245cb301d5 100644 --- a/drivers/dma/idxd/debugfs.c +++ b/drivers/dma/idxd/debugfs.c @@ -66,7 +66,7 @@ static int debugfs_evl_show(struct seq_file *s, void *d) if (!evl || !evl->log) return 0;
- spin_lock(&evl->lock); + mutex_lock(&evl->lock);
evl_status.bits = ioread64(idxd->reg_base + IDXD_EVLSTATUS_OFFSET); t = evl_status.tail; @@ -87,7 +87,7 @@ static int debugfs_evl_show(struct seq_file *s, void *d) dump_event_entry(idxd, s, i, &count, processed); }
- spin_unlock(&evl->lock); + mutex_unlock(&evl->lock); return 0; }
diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c index ecfdf4a8f1f83..c41ef195eeb9f 100644 --- a/drivers/dma/idxd/device.c +++ b/drivers/dma/idxd/device.c @@ -775,7 +775,7 @@ static int idxd_device_evl_setup(struct idxd_device *idxd) goto err_alloc; }
- spin_lock(&evl->lock); + mutex_lock(&evl->lock); evl->log = addr; evl->dma = dma_addr; evl->log_size = size; @@ -796,7 +796,7 @@ static int idxd_device_evl_setup(struct idxd_device *idxd) gencfg.evl_en = 1; iowrite32(gencfg.bits, idxd->reg_base + IDXD_GENCFG_OFFSET);
- spin_unlock(&evl->lock); + mutex_unlock(&evl->lock); return 0;
err_alloc: @@ -819,7 +819,7 @@ static void idxd_device_evl_free(struct idxd_device *idxd) if (!gencfg.evl_en) return;
- spin_lock(&evl->lock); + mutex_lock(&evl->lock); gencfg.evl_en = 0; iowrite32(gencfg.bits, idxd->reg_base + IDXD_GENCFG_OFFSET);
@@ -836,7 +836,7 @@ static void idxd_device_evl_free(struct idxd_device *idxd) evl_dma = evl->dma; evl->log = NULL; evl->size = IDXD_EVL_SIZE_MIN; - spin_unlock(&evl->lock); + mutex_unlock(&evl->lock);
dma_free_coherent(dev, evl_log_size, evl_log, evl_dma); } diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h index d0f5db6cf1eda..df91472f0f5b1 100644 --- a/drivers/dma/idxd/idxd.h +++ b/drivers/dma/idxd/idxd.h @@ -293,7 +293,7 @@ struct idxd_driver_data {
struct idxd_evl { /* Lock to protect event log access. */ - spinlock_t lock; + struct mutex lock; void *log; dma_addr_t dma; /* Total size of event log = number of entries * entry size. */ diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c index 4954adc6bb609..264c4e47d7cca 100644 --- a/drivers/dma/idxd/init.c +++ b/drivers/dma/idxd/init.c @@ -354,7 +354,7 @@ static int idxd_init_evl(struct idxd_device *idxd) if (!evl) return -ENOMEM;
- spin_lock_init(&evl->lock); + mutex_init(&evl->lock); evl->size = IDXD_EVL_SIZE_MIN;
idxd_name = dev_name(idxd_confdev(idxd)); diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c index 348aa21389a9f..8dc029c865515 100644 --- a/drivers/dma/idxd/irq.c +++ b/drivers/dma/idxd/irq.c @@ -363,7 +363,7 @@ static void process_evl_entries(struct idxd_device *idxd) evl_status.bits = 0; evl_status.int_pending = 1;
- spin_lock(&evl->lock); + mutex_lock(&evl->lock); /* Clear interrupt pending bit */ iowrite32(evl_status.bits_upper32, idxd->reg_base + IDXD_EVLSTATUS_OFFSET + sizeof(u32)); @@ -380,7 +380,7 @@ static void process_evl_entries(struct idxd_device *idxd)
evl_status.head = h; iowrite32(evl_status.bits_lower32, idxd->reg_base + IDXD_EVLSTATUS_OFFSET); - spin_unlock(&evl->lock); + mutex_unlock(&evl->lock); }
irqreturn_t idxd_misc_thread(int vec, void *data)