Re: [PATCH -next] scsi: efct: Use GFP_ATOMIC under spin lock

[Yang Yingliang <yangyingliang@xxxxxxxxxx>]

On 2021/12/21 22:28, Christoph Hellwig wrote:
> On Tue, Dec 21, 2021 at 07:37:06PM +0800, Yang Yingliang wrote:
> > A spin lock is taken here so we should use GFP_ATOMIC.
> >
> > Fixes: efac162a4e4d ("scsi: efct: Don't pass GFP_DMA to dma_alloc_coherent()")
> No, it does not fix that commit.  The driver did sleeping allocations
> even before the commit.
>
> But wher is "here"?  Can we look into not holding that lock over an
> allocation if it is preferable?  If not we should at least pass down
> the gfp_flags so that only the caller(s) that can't sleep pass GFP_ATOMIC.

According the comment of els_ios_lock, it's used to protect els ios 
list, I think we

can move down the spin lock like this:


--- a/drivers/scsi/elx/libefc/efc_els.c
+++ b/drivers/scsi/elx/libefc/efc_els.c
@@ -46,8 +46,6 @@ 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);
@@ -88,6 +86,8 @@ 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;