[PATCH -next] scsi: efct: don't use GFP_KERNEL under spin lock

[PATCH -next] scsi: efct: don't use GFP_KERNEL under spin lock

[Yang Yingliang]

GFP_KERNEL/GFP_DMA can't be used under a spin lock, according the
comment of els_ios_lock, it's used to protect els ios list, so we
can move down the spin lock to avoid using this flag under the lock.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 8f406ef72859 ("scsi: elx: libefc: Extended link Service I/O handling")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 drivers/scsi/elx/libefc/efc_els.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/elx/libefc/efc_els.c b/drivers/scsi/elx/libefc/efc_els.c
index 7bb4f9aad2c8..cec6a2f649b3 100644
--- a/drivers/scsi/elx/libefc/efc_els.c
+++ b/drivers/scsi/elx/libefc/efc_els.c
@@ -46,18 +46,14 @@ efc_els_io_alloc_size(struct efc_node *node, u32 reqlen, u32 rsplen)
 
 	efc = node->efc;
 
-	spin_lock_irqsave(&node->els_ios_lock, flags);
-
 	if (!node->els_io_enabled) {
 		efc_log_err(efc, "els io alloc disabled\n");
-		spin_unlock_irqrestore(&node->els_ios_lock, flags);
 		return NULL;
 	}
 
 	els = mempool_alloc(efc->els_io_pool, GFP_ATOMIC);
 	if (!els) {
 		atomic_add_return(1, &efc->els_io_alloc_failed_count);
-		spin_unlock_irqrestore(&node->els_ios_lock, flags);
 		return NULL;
 	}
 
@@ -74,7 +70,6 @@ efc_els_io_alloc_size(struct efc_node *node, u32 reqlen, u32 rsplen)
 					      &els->io.req.phys, GFP_KERNEL);
 	if (!els->io.req.virt) {
 		mempool_free(els, efc->els_io_pool);
-		spin_unlock_irqrestore(&node->els_ios_lock, flags);
 		return NULL;
 	}
 
@@ -88,6 +83,8 @@ efc_els_io_alloc_size(struct efc_node *node, u32 reqlen, u32 rsplen)
 		els = NULL;
 	}
 
+	spin_lock_irqsave(&node->els_ios_lock, flags);
+
 	if (els) {
 		/* initialize fields */
 		els->els_retries_remaining = EFC_FC_ELS_DEFAULT_RETRIES;
-- 
2.25.1

Re: [PATCH -next] scsi: efct: don't use GFP_KERNEL under spin lock

[Maurizio Lombardi]

On Mon, Jan 10, 2022 at 07:18:38PM +0800, Yang Yingliang wrote:
> +	spin_lock_irqsave(&node->els_ios_lock, flags);
> +
>  	if (els) {
>  		/* initialize fields */
>  		els->els_retries_remaining = EFC_FC_ELS_DEFAULT_RETRIES;

If the els pointer is NULL you will lock the spinlock and disable the interrupts
for no reason, maybe you can just protect the list_add_tail()?

+spin_lock_irqsave(&node->els_ios_lock, flags);
 list_add_tail(&els->list_entry, &node->els_ios_list);
+spin_unlock_irqrestore(&node->els_ios_lock, flags);

Maurizio

Re: [PATCH -next] scsi: efct: don't use GFP_KERNEL under spin lock

[Yang Yingliang]

Hi,

On 2022/1/10 19:19, Maurizio Lombardi wrote:
> On Mon, Jan 10, 2022 at 07:18:38PM +0800, Yang Yingliang wrote:
>> +	spin_lock_irqsave(&node->els_ios_lock, flags);
>> +
>>   	if (els) {
>>   		/* initialize fields */
>>   		els->els_retries_remaining = EFC_FC_ELS_DEFAULT_RETRIES;
> If the els pointer is NULL you will lock the spinlock and disable the interrupts
> for no reason, maybe you can just protect the list_add_tail()?
>
> +spin_lock_irqsave(&node->els_ios_lock, flags);
>   list_add_tail(&els->list_entry, &node->els_ios_list);
> +spin_unlock_irqrestore(&node->els_ios_lock, flags);
Yes, it's better, I will send a v2 later.

Thanks,
Yang
>
> Maurizio
>
> .