Hi Lijun,
On 2023-12-20 at 19:17:20 -0600, Lijun Pan wrote:
>
>
> On 12/19/2023 9:53 PM, Rex Zhang wrote:
> > The drain_workqueue() is not in a locked context. In the multi-task case,
> > it's possible to call queue_work() when drain_workqueue() is ongoing, then
> > it can cause Call Trace due to pushing a work into a draining workqueue:
> > 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 original locker for event log was spinlock, drain_workqueue() can't
>
> s/locker/lock
>
> Other than that,
>
> Tested-by: Lijun Pan <lijun.pan@xxxxxxxxx>
> Reviewed-by: Lijun Pan <lijun.pan@xxxxxxxxx>
Thanks for pointing out.
Will update.
> > be in a spinlocked context because it may cause task rescheduling. The
> > spinlock was called in thread and irq thread context, the current usages
> > does not require a spinlock for event log, so it's feasible to convert
> > spinlock to mutex.
> > For putting drain_workqueue() into a locked context, convert the spinlock
> > to mutex, then lock drain_workqueue() by mutex.
> >
> > Fixes: c40bd7d9737b ("dmaengine: idxd: process user page faults for completion record")
> > Signed-off-by: Rex Zhang <rex.zhang@xxxxxxxxx>
> > Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> > Reviewed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> > ---
> > 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 0423655f5a88..556cac187612 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 = evl->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 9cfbd9b14c4c..7f689b3aff65 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);
> > h = evl->head;
> > evl_status.bits = ioread64(idxd->reg_base + IDXD_EVLSTATUS_OFFSET);
> > @@ -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 8f754f922217..042e076a6f2a 100644
> > --- a/drivers/dma/idxd/device.c
> > +++ b/drivers/dma/idxd/device.c
> > @@ -770,7 +770,7 @@ 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;
> > @@ -791,7 +791,7 @@ 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:
> > @@ -811,7 +811,7 @@ 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);
> > @@ -826,7 +826,7 @@ static void idxd_device_evl_free(struct idxd_device *idxd)
> > bitmap_free(evl->bmap);
> > evl->log = NULL;
> > evl->size = IDXD_EVL_SIZE_MIN;
> > - spin_unlock(&evl->lock);
> > + mutex_unlock(&evl->lock);
> > }
> > static void idxd_group_config_write(struct idxd_group *group)
> > diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
> > index 1e89c80a07fc..b925c972b99b 100644
> > --- a/drivers/dma/idxd/idxd.h
> > +++ b/drivers/dma/idxd/idxd.h
> > @@ -283,7 +283,7 @@ 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 0eb1c827a215..611101f99405 100644
> > --- a/drivers/dma/idxd/init.c
> > +++ b/drivers/dma/idxd/init.c
> > @@ -351,7 +351,7 @@ 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->evl_cache = kmem_cache_create(dev_name(idxd_confdev(idxd)),
> > diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
> > index 2183d7f9cdbd..3037eda986de 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));
> > @@ -381,7 +381,7 @@ static void process_evl_entries(struct idxd_device *idxd)
> > evl->head = h;
> > 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)
