linux-kernel - Re: [BUG] scsi/qla2xxx: a possible sleep-in-atomic bug in qlt_get

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Date:   Wed, 13 Dec 2017 15:38:20 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     James Bottomley <jejb@...ux.vnet.ibm.com>,
        qla2xxx-upstream@...gic.com, martin.petersen@...cle.com
Cc:     linux-scsi@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] scsi/qla2xxx: a possible sleep-in-atomic bug in qlt_get_tag


On 2017/12/13 12:42, James Bottomley wrote:
> On Wed, 2017-12-13 at 11:18 +0800, Jia-Ju Bai wrote:
>> The driver may sleep under a spinlock.
>> The function call paths are:
>> qlt_handle_abts_recv_work (acquire the spinlock)
>>     qlt_response_pkt_all_vps
>>       qlt_response_pkt
>>         qlt_handle_cmd_for_atio
>>           qlt_get_tag
>>             percpu_ida_alloc --> may sleep
>>
>> qla82xx_msix_rsp_q (acquire the spinlock)
>>     qla24xx_process_response_queue
>>       qlt_handle_abts_recv
>>         qlt_response_pkt_all_vps
>>           qlt_response_pkt
>>             qlt_handle_cmd_for_atio
>>               qlt_get_tag
>>                 percpu_ida_alloc --> may sleep-in-atomic
>>
>> qla24xx_intr_handler (acquire the spinlock)
>>     qla24xx_process_response_queue
>>       qlt_handle_abts_recv
>>         qlt_response_pkt
>>           qlt_handle_cmd_for_atio
>>             qlt_get_tag
>>               percpu_ida_alloc --> may sleep
>>
>> I do not find a good way to fix it, so I only report.
>> This possible bug is found by my static analysis tool (DSAC) and
>> checked by my code review.
> The report is incorrect: percpu_ida_alloc with state==TASK_RUNNING is
> atomic (and interrupt) safe which appears to be the case here.
>
> James
>

Thanks for your reply :)
I have checked the definition of percpu_ida_alloc, and I think you are 
right.
Sorry for my incorrect bug report.


Thanks,
Jia-Ju Bai