Re: [PATCH] scsi: fix race condition when removing target

From: Jason Yan <yanaijie@huawei.com>
To: James Bottomley <jejb@linux.vnet.ibm.com>,
	Bart Van Assche <Bart.VanAssche@wdc.com>,
	"hch@lst.de" <hch@lst.de>
Cc: "zhaohongjiang@huawei.com" <zhaohongjiang@huawei.com>,
	"jthumshirn@suse.de" <jthumshirn@suse.de>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"hare@suse.de" <hare@suse.de>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"miaoxie@huawei.com" <miaoxie@huawei.com>
Subject: Re: [PATCH] scsi: fix race condition when removing target
Date: Wed, 6 Dec 2017 10:43:47 +0800	[thread overview]
Message-ID: <5A275963.4010000@huawei.com> (raw)
In-Reply-To: <1512526028.29950.4.camel@linux.vnet.ibm.com>

> execute_in_process_context() is supposed to produce us a context
> whenever the local context isn't available, and that's supposed to
> include when interrupts are disabled as in spin_lock_irqsave().
>
> So let me ask this another way: have you seen this deadlock (which
> would mean we have a bug in execute_process_context())?
>
> James
>
>

I havn't seen this dead lock but in_interrupt() do not check whether
the interrupts are disabled. Please refer to the definition of
in_interrupt().

#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK\
				 | NMI_MASK))
#define in_interrupt()		(irq_count())

Jason

> .
>