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From: Jan Kara <jack@suse.cz>
To: Nixiaoming <nixiaoming@huawei.com>
Cc: Jan Kara <jack@suse.cz>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Amir Goldstein <amir73il@gmail.com>
Subject: Re: [PATCH v3 7/8] fanotify: support reporting thread id instead of process id
Date: Tue, 16 Oct 2018 14:06:28 +0200	[thread overview]
Message-ID: <20181016120628.GL18918@quack2.suse.cz> (raw)
In-Reply-To: <E490CD805F7529488761C40FD9D26EF12A801F5E@DGGEMM527-MBS.china.huawei.com>

On Fri 12-10-18 02:43:02, Nixiaoming wrote:
> On Thu, Oct 11, 2018 at 6:16 PM Jan Kara <mailto:jack@suse.cz> wrote:
> >On Thu 04-10-18 00:25:38, Amir Goldstein wrote:
> >> In order to identify which thread triggered the event in a
> >> multi-threaded program, add the FAN_EVENT_INFO_TID flag in fanotify_init
> >> to opt-in for reporting the event creator's thread id information.
> >> 
> >> Signed-off-by: nixiaoming <nixiaoming@huawei.com>
> >> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> >
> >Just one question occurred to me (after discussion with a colleague about
> >this feature): Ming, why do you actually need to know thread ID and
> >thread-group ID is not enough? Also note that standard glibc threading
> >functions are *not* going to be compatible with the ID returned from
> >fanotify (e.g. it will be different from POSIX thread ID as returned by
> >pthread_self()). So the feature is somewhat difficult to use from
> >userspace... (at least you could use gettid() systemcall to get the ID of
> >current thread but there's not glibc wrapper for it).
> >
> 
> When using fanotify to monitor system critical directories or files,
>  the monitor and event trigger are not the same process.
> The monitoring task wants to know which task triggers the event.
> If the event is triggered by multiple threads, 
> I hope to know which thread is triggered by the task,
>  can't see the pthread id here, but I can see the tid.

OK, thanks for clarification.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2018-10-16 19:56 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-03 21:25 [PATCH v3 0/8] New fanotify event info API Amir Goldstein
2018-10-03 21:25 ` [PATCH v3 1/8] fanotify: fix collision of internal and uapi mark flags Amir Goldstein
2018-10-03 21:25 ` [PATCH v3 2/8] fsnotify: generalize handling of extra event flags Amir Goldstein
2018-10-03 21:25 ` [PATCH v3 3/8] fanotify: simplify handling of FAN_ONDIR Amir Goldstein
2018-10-03 21:25 ` [PATCH v3 4/8] fanotify: deprecate uapi FAN_ALL_* constants Amir Goldstein
2018-10-03 21:25 ` [PATCH v3 5/8] fsnotify: convert runtime BUG_ON() to BUILD_BUG_ON() Amir Goldstein
2018-10-03 21:25 ` [PATCH v3 6/8] fanotify: add BUILD_BUG_ON() to count the bits of fanotify constants Amir Goldstein
2018-10-04  8:41   ` Jan Kara
2018-10-04 10:24     ` Amir Goldstein
2018-10-03 21:25 ` [PATCH v3 7/8] fanotify: support reporting thread id instead of process id Amir Goldstein
2018-10-04  8:46   ` Jan Kara
2018-10-04 10:27     ` Amir Goldstein
2018-10-11 10:16   ` Jan Kara
2018-10-12  2:43     ` Nixiaoming
2018-10-16 12:06       ` Jan Kara [this message]
2018-10-03 21:25 ` [PATCH v3 8/8] fsnotify: optimize away srcu_read_lock() for events on directories Amir Goldstein
2018-10-04  9:09   ` Jan Kara
2018-10-04 10:30     ` Amir Goldstein
2018-10-04 11:26       ` Jan Kara
2018-10-04 22:05         ` Amir Goldstein

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