From: Jan Kara <jack@suse.cz>
To: Matthew Bobrowski <repnop@google.com>
Cc: jack@suse.cz, amir73il@gmail.com, christian.brauner@ubuntu.com,
linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/2] fanotify: Add pidfd support to the fanotify API
Date: Mon, 19 Apr 2021 12:21:39 +0200 [thread overview]
Message-ID: <20210419102139.GD8706@quack2.suse.cz> (raw)
In-Reply-To: <e6cd967f45381d20d67c9d5a3e49e3cb9808f65b.1618527437.git.repnop@google.com>
On Fri 16-04-21 09:22:25, Matthew Bobrowski wrote:
> Introduce a new flag FAN_REPORT_PIDFD for fanotify_init(2) which
> allows userspace applications to control whether a pidfd is to be
> returned instead of a pid for `struct fanotify_event_metadata.pid`.
>
> FAN_REPORT_PIDFD is mutually exclusive with FAN_REPORT_TID as the
> pidfd API is currently restricted to only support pidfd generation for
> thread-group leaders. Attempting to set them both when calling
> fanotify_init(2) will result in -EINVAL being returned to the
> caller. As the pidfd API evolves and support is added for tids, this
> is something that could be relaxed in the future.
>
> If pidfd creation fails, the pid in struct fanotify_event_metadata is
> set to FAN_NOPIDFD(-1). Falling back and providing a pid instead of a
> pidfd on pidfd creation failures was considered, although this could
> possibly lead to confusion and unpredictability within userspace
> applications as distinguishing between whether an actual pidfd or pid
> was returned could be difficult, so it's best to be explicit.
>
> Signed-off-by: Matthew Bobrowski <repnop@google.com>
Overall this looks OK to me. Just one style nit & one question below in
addition to what Amir wrote.
> ---
> fs/notify/fanotify/fanotify_user.c | 33 +++++++++++++++++++++++++++---
> include/linux/fanotify.h | 2 +-
> include/uapi/linux/fanotify.h | 2 ++
> 3 files changed, 33 insertions(+), 4 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 9e0c1afac8bd..fd8ae88796a8 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -329,7 +329,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
> struct fanotify_info *info = fanotify_event_info(event);
> unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
> struct file *f = NULL;
> - int ret, fd = FAN_NOFD;
> + int ret, pidfd, fd = FAN_NOFD;
> int info_type = 0;
>
> pr_debug("%s: group=%p event=%p\n", __func__, group, event);
> @@ -340,7 +340,25 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
> metadata.vers = FANOTIFY_METADATA_VERSION;
> metadata.reserved = 0;
> metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS;
> - metadata.pid = pid_vnr(event->pid);
> +
> + if (FAN_GROUP_FLAG(group, FAN_REPORT_PIDFD) &&
> + pid_has_task(event->pid, PIDTYPE_TGID)) {
Please align the rest of the condition to the opening brace. I.e., like:
if (FAN_GROUP_FLAG(group, FAN_REPORT_PIDFD) &&
pid_has_task(event->pid, PIDTYPE_TGID)) {
BTW, why is the pid_has_task() check here? And why is it OK to fall back to
returning pid if pid_has_task() is false?
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2021-04-19 10:22 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 23:21 [PATCH 0/2] fanotify: Adding pidfd support to the fanotify API Matthew Bobrowski
2021-04-15 23:22 ` [PATCH 1/2] pidfd_create(): remove static qualifier and declare pidfd_create() in linux/pid.h Matthew Bobrowski
2021-04-19 10:13 ` Jan Kara
2021-04-19 12:50 ` Christian Brauner
2021-04-20 0:17 ` Matthew Bobrowski
2021-04-15 23:22 ` [PATCH 2/2] fanotify: Add pidfd support to the fanotify API Matthew Bobrowski
2021-04-16 6:27 ` Amir Goldstein
2021-04-16 7:05 ` Matthew Bobrowski
2021-04-16 7:53 ` Amir Goldstein
2021-04-16 8:08 ` Matthew Bobrowski
2021-04-19 13:02 ` Christian Brauner
2021-04-19 10:21 ` Jan Kara [this message]
2021-04-20 1:35 ` Matthew Bobrowski
2021-04-19 13:20 ` Christian Brauner
2021-04-19 13:53 ` Amir Goldstein
2021-04-19 14:44 ` Christian Brauner
2021-04-19 13:55 ` Jan Kara
2021-04-19 15:02 ` Christian Brauner
2021-04-20 2:36 ` Matthew Bobrowski
2021-04-21 8:04 ` Jan Kara
2021-04-21 9:29 ` Amir Goldstein
2021-04-21 10:00 ` Jan Kara
2021-04-21 10:12 ` Amir Goldstein
2021-04-21 13:48 ` Jan Kara
2021-04-21 14:46 ` Christian Brauner
2021-04-22 23:06 ` Matthew Bobrowski
2021-04-23 7:39 ` Amir Goldstein
2021-04-23 8:02 ` Matthew Bobrowski
2021-04-23 8:14 ` Amir Goldstein
2021-04-26 10:26 ` Matthew Bobrowski
2021-04-26 11:11 ` Amir Goldstein
2021-04-27 3:35 ` Matthew Bobrowski
2021-04-27 5:14 ` Amir Goldstein
2021-04-28 22:53 ` Matthew Bobrowski
2021-04-19 12:34 ` [PATCH 0/2] fanotify: Adding " Christian Brauner
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