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From: Nixiaoming <nixiaoming@huawei.com>
To: Jan Kara <jack@suse.cz>
Cc: "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: Fri, 12 Oct 2018 02:43:02 +0000	[thread overview]
Message-ID: <E490CD805F7529488761C40FD9D26EF12A801F5E@DGGEMM527-MBS.china.huawei.com> (raw)
In-Reply-To: <20181011101625.GA9467@quack2.suse.cz>

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.

Thanks

  reply	other threads:[~2018-10-12 10:13 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 [this message]
2018-10-16 12:06       ` Jan Kara
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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