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From: "dalias@aerifal.cx" <dalias@aerifal.cx>
To: tangyizhou <tangyizhou@huawei.com>
Cc: "musl@lists.openwall.com" <musl@lists.openwall.com>,
	"Wanghui (John)" <john.wanghui@huawei.com>,
	"Huangshuai (OSLab)" <elvis.huang@huawei.com>
Subject: Re: [musl] Fix the return value of pthread_getschedparam in musl libc
Date: Thu, 21 May 2020 22:26:29 -0400	[thread overview]
Message-ID: <20200522022628.GP1079@brightrain.aerifal.cx> (raw)
In-Reply-To: <4EB7132F5A45D144AC896FC29A83F192011628FB@DGGEML521-MBS.china.huawei.com>

On Fri, May 22, 2020 at 01:53:02AM +0000, tangyizhou wrote:
> > What is the situation under which SYS_sched_getparam can succeed
> > but SYS_sched_getscheduler can fail? The Linux man page
> > documenting the syscall:
> 
> There is a timing issue between two syscalls. Think about a concurrent scenario:
> Thread A calls pthread_getschedparam() to query the information of
> thread B.. After SYS_sched_getparam succeeds and before
> SYS_sched_getscheduler starts, thread B is killed, then
> SYS_sched_getparam returns -ESRCH.

There's not such an issue. t->killlock is held so that this can't
happen, and more importantly, so that the thread can't exit and the
tid be reassigned to a new thread or process that would wrongly be
acted upon.

Rich

  reply	other threads:[~2020-05-22  2:26 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20  2:09 tangyizhou
2020-05-20 15:50 ` dalias
2020-05-22  1:53   ` tangyizhou
2020-05-22  2:26     ` dalias [this message]
2020-05-28 14:27       ` tangyizhou
2020-05-28 16:09         ` dalias

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