diff mbox series

[RESEND] nvme: Use spin_lock_irqsave() when taking the ctrl->lock

Message ID 20200812210119.7155-1-logang@deltatee.com (mailing list archive)
State New, archived
Headers show
Series [RESEND] nvme: Use spin_lock_irqsave() when taking the ctrl->lock | expand

Commit Message

Logan Gunthorpe Aug. 12, 2020, 9:01 p.m. UTC 
When locking the ctrl->lock spinlock IRQs need to be disabled to avoid a
dead lock. The new spin_lock() calls recently added produce the
following lockdep warning when running the blktest nvme/003:

    ================================
    WARNING: inconsistent lock state
    --------------------------------
    inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
    ksoftirqd/2/22 [HC0[0]:SC1[1]:HE0:SE0] takes:
    ffff888276a8c4c0 (&ctrl->lock){+.?.}-{2:2}, at: nvme_keep_alive_end_io+0x50/0xc0
    {SOFTIRQ-ON-W} state was registered at:
      lock_acquire+0x164/0x500
      _raw_spin_lock+0x28/0x40
      nvme_get_effects_log+0x37/0x1c0
      nvme_init_identify+0x9e4/0x14f0
      nvme_reset_work+0xadd/0x2360
      process_one_work+0x66b/0xb70
      worker_thread+0x6e/0x6c0
      kthread+0x1e7/0x210
      ret_from_fork+0x22/0x30
    irq event stamp: 1449221
    hardirqs last  enabled at (1449220): [<ffffffff81c58e69>] ktime_get+0xf9/0x140
    hardirqs last disabled at (1449221): [<ffffffff83129665>] _raw_spin_lock_irqsave+0x25/0x60
    softirqs last  enabled at (1449210): [<ffffffff83400447>] __do_softirq+0x447/0x595
    softirqs last disabled at (1449215): [<ffffffff81b489b5>] run_ksoftirqd+0x35/0x50

    other info that might help us debug this:
     Possible unsafe locking scenario:

           CPU0
           ----
      lock(&ctrl->lock);
      <Interrupt>
        lock(&ctrl->lock);

     *** DEADLOCK ***

    no locks held by ksoftirqd/2/22.

    stack backtrace:
    CPU: 2 PID: 22 Comm: ksoftirqd/2 Not tainted 5.8.0-rc4-eid-vmlocalyes-dbg-00157-g7236657c6b3a #1450
    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
    Call Trace:
     dump_stack+0xc8/0x11a
     print_usage_bug.cold.63+0x235/0x23e
     mark_lock+0xa9c/0xcf0
     __lock_acquire+0xd9a/0x2b50
     lock_acquire+0x164/0x500
     _raw_spin_lock_irqsave+0x40/0x60
     nvme_keep_alive_end_io+0x50/0xc0
     blk_mq_end_request+0x158/0x210
     nvme_complete_rq+0x146/0x500
     nvme_loop_complete_rq+0x26/0x30 [nvme_loop]
     blk_done_softirq+0x187/0x1e0
     __do_softirq+0x118/0x595
     run_ksoftirqd+0x35/0x50
     smpboot_thread_fn+0x1d3/0x310
     kthread+0x1e7/0x210
     ret_from_fork+0x22/0x30

Fixes: be93e87e7802 ("nvme: support for multiple Command Sets Supported and Effects log pages")
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
 drivers/nvme/host/core.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)


base-commit: 4d3c0eaf0d44a4f8f7d53b7835e670eafc96c450
--
2.20.1

Comments

Keith Busch Aug. 12, 2020, 9:19 p.m. UTC | #1 
On Wed, Aug 12, 2020 at 03:01:19PM -0600, Logan Gunthorpe wrote:
> @@ -2971,15 +2971,16 @@ int nvme_get_log(struct nvme_ctrl *ctrl, u32 nsid, u8 log_page, u8 lsp, u8 csi,
>  static struct nvme_cel *nvme_find_cel(struct nvme_ctrl *ctrl, u8 csi)
>  {
>  	struct nvme_cel *cel, *ret = NULL;
> +	unsigned long flags;
> 
> -	spin_lock(&ctrl->lock);
> +	spin_lock_irqsave(&ctrl->lock, flags);
>  	list_for_each_entry(cel, &ctrl->cels, entry) {
>  		if (cel->csi == csi) {
>  			ret = cel;
>  			break;
>  		}
>  	}
> -	spin_unlock(&ctrl->lock);
> +	spin_unlock_irqrestore(&ctrl->lock, flags);
> 
>  	return ret;
>  }
> @@ -2988,6 +2989,7 @@ static int nvme_get_effects_log(struct nvme_ctrl *ctrl, u8 csi,
>  				struct nvme_effects_log **log)
>  {
>  	struct nvme_cel *cel = nvme_find_cel(ctrl, csi);
> +	unsigned long flags;
>  	int ret;
> 
>  	if (cel)
> @@ -3006,9 +3008,9 @@ static int nvme_get_effects_log(struct nvme_ctrl *ctrl, u8 csi,
> 
>  	cel->csi = csi;
> 
> -	spin_lock(&ctrl->lock);
> +	spin_lock_irqsave(&ctrl->lock, flags);
>  	list_add_tail(&cel->entry, &ctrl->cels);
> -	spin_unlock(&ctrl->lock);
> +	spin_unlock_irqrestore(&ctrl->lock, flags);
>  out:
>  	*log = &cel->log;
>  	return 0;
> 

Neither of these are ever called from an interrupt disabled context,
correct? If so, you can just use spin_lock_irq() without saving the
current irq state.
Logan Gunthorpe Aug. 12, 2020, 9:31 p.m. UTC | #2 
On 2020-08-12 3:19 p.m., Keith Busch wrote:
> On Wed, Aug 12, 2020 at 03:01:19PM -0600, Logan Gunthorpe wrote:
>> @@ -2971,15 +2971,16 @@ int nvme_get_log(struct nvme_ctrl *ctrl, u32 nsid, u8 log_page, u8 lsp, u8 csi,
>>  static struct nvme_cel *nvme_find_cel(struct nvme_ctrl *ctrl, u8 csi)
>>  {
>>  	struct nvme_cel *cel, *ret = NULL;
>> +	unsigned long flags;
>>
>> -	spin_lock(&ctrl->lock);
>> +	spin_lock_irqsave(&ctrl->lock, flags);
>>  	list_for_each_entry(cel, &ctrl->cels, entry) {
>>  		if (cel->csi == csi) {
>>  			ret = cel;
>>  			break;
>>  		}
>>  	}
>> -	spin_unlock(&ctrl->lock);
>> +	spin_unlock_irqrestore(&ctrl->lock, flags);
>>
>>  	return ret;
>>  }
>> @@ -2988,6 +2989,7 @@ static int nvme_get_effects_log(struct nvme_ctrl *ctrl, u8 csi,
>>  				struct nvme_effects_log **log)
>>  {
>>  	struct nvme_cel *cel = nvme_find_cel(ctrl, csi);
>> +	unsigned long flags;
>>  	int ret;
>>
>>  	if (cel)
>> @@ -3006,9 +3008,9 @@ static int nvme_get_effects_log(struct nvme_ctrl *ctrl, u8 csi,
>>
>>  	cel->csi = csi;
>>
>> -	spin_lock(&ctrl->lock);
>> +	spin_lock_irqsave(&ctrl->lock, flags);
>>  	list_add_tail(&cel->entry, &ctrl->cels);
>> -	spin_unlock(&ctrl->lock);
>> +	spin_unlock_irqrestore(&ctrl->lock, flags);
>>  out:
>>  	*log = &cel->log;
>>  	return 0;
>>
> 
> Neither of these are ever called from an interrupt disabled context,
> correct? If so, you can just use spin_lock_irq() without saving the
> current irq state.

Yes, I believe that is correct. I'll send a v2 shortly.

Thanks,

Logan
diff mbox series

Patch

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 15abc00db3d3..312614467adb 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2971,15 +2971,16 @@  int nvme_get_log(struct nvme_ctrl *ctrl, u32 nsid, u8 log_page, u8 lsp, u8 csi,
 static struct nvme_cel *nvme_find_cel(struct nvme_ctrl *ctrl, u8 csi)
 {
 	struct nvme_cel *cel, *ret = NULL;
+	unsigned long flags;

-	spin_lock(&ctrl->lock);
+	spin_lock_irqsave(&ctrl->lock, flags);
 	list_for_each_entry(cel, &ctrl->cels, entry) {
 		if (cel->csi == csi) {
 			ret = cel;
 			break;
 		}
 	}
-	spin_unlock(&ctrl->lock);
+	spin_unlock_irqrestore(&ctrl->lock, flags);

 	return ret;
 }
@@ -2988,6 +2989,7 @@  static int nvme_get_effects_log(struct nvme_ctrl *ctrl, u8 csi,
 				struct nvme_effects_log **log)
 {
 	struct nvme_cel *cel = nvme_find_cel(ctrl, csi);
+	unsigned long flags;
 	int ret;

 	if (cel)
@@ -3006,9 +3008,9 @@  static int nvme_get_effects_log(struct nvme_ctrl *ctrl, u8 csi,

 	cel->csi = csi;

-	spin_lock(&ctrl->lock);
+	spin_lock_irqsave(&ctrl->lock, flags);
 	list_add_tail(&cel->entry, &ctrl->cels);
-	spin_unlock(&ctrl->lock);
+	spin_unlock_irqrestore(&ctrl->lock, flags);
 out:
 	*log = &cel->log;
 	return 0;