linux-kernel - Re: [PATCH] [SCSI] wd719x: Avoid calling request

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Message-ID: <5c68b70f-e20e-08e4-66f9-2090806b0078@huawei.com>
Date:   Thu, 15 Sep 2016 15:14:25 +0100
From:   John Garry <john.garry@...wei.com>
To:     Vaishali Thakkar <vaishali.thakkar@...cle.com>,
        <jejb@...ux.vnet.ibm.com>
CC:     <linux-kernel@...r.kernel.org>, <martin.petersen@...cle.com>,
        <linux-scsi@...r.kernel.org>
Subject: Re: [PATCH] [SCSI] wd719x: Avoid calling request_firmware under
 spinlock

On 15/09/2016 15:08, John Garry wrote:
> On 15/09/2016 14:48, Vaishali Thakkar wrote:
>> It is preferrable to use request_firmware where sleeping is
>> allowed. Using it under spinlock can cause blocking. Here,
>> the function wd719x_chip_init calls request_firmware while
>> holding a spinlock. So, let's access it outside the spinlock.
>>
>> Coccinelle is used to detect the issue.
>>
>> Signed-off-by: Vaishali Thakkar <vaishali.thakkar@...cle.com>
>> ---
>> Please note that the patch is compile-tested only. And this change
>> may require driver testing.
>> ---
>>  drivers/scsi/wd719x.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/wd719x.c b/drivers/scsi/wd719x.c
>> index e3da1a2..b8e57f3 100644
>> --- a/drivers/scsi/wd719x.c
>> +++ b/drivers/scsi/wd719x.c
>> @@ -518,13 +518,14 @@ static int wd719x_host_reset(struct scsi_cmnd *cmd)
>>      int result;
>>
>>      dev_info(&wd->pdev->dev, "host reset requested\n");
>> -    spin_lock_irqsave(wd->sh->host_lock, flags);
>> +
>
> In the version of code I have flags is only used for this spinlock, so
> can flags be removed?

I see we're just relocating the spinlock, so ignore me

>
>>      /* Try to reinit the RISC */
>>      if (wd719x_chip_init(wd) == 0)
>>          result = SUCCESS;
>>      else
>>          result = FAILED;
>>
>> +    spin_lock_irqsave(wd->sh->host_lock, flags);
>>      /* flush all SCBs */
>>      list_for_each_entry_safe(scb, tmp, &wd->active_scbs, list) {
>>          struct scsi_cmnd *tmp_cmd = scb->cmd;
>>
>
>
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