From: Abhinav Kumar <quic_abhinavk@quicinc.com> To: Johannes Berg <johannes@sipsolutions.net>, <linux-kernel@vger.kernel.org> Cc: rafael@kernel.org, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, swboyd@chromium.org, khsieh@codeaurora.org, nganji@codeaurora.org, seanpaul@chromium.org, gregkh@linuxfoundation.org, dmitry.baryshkov@linaro.org, aravindh@codeaurora.org, freedreno@lists.freedesktop.org Subject: Re: [PATCH] devcoredump: increase the device delete timeout to 10 mins Date: Tue, 8 Feb 2022 17:55:18 -0800 [thread overview] Message-ID: <b60d30cf-e435-49c4-a251-b910bc2e94ae@quicinc.com> (raw) In-Reply-To: <c2a6e29063793eecc5c65d32af9d826544404ecc.camel@sipsolutions.net> Hi Johannes On 2/8/2022 1:54 PM, Johannes Berg wrote: > On Tue, 2022-02-08 at 13:40 -0800, Abhinav Kumar wrote: >>> >> I am checking what usermode sees and will get back ( I didnt see an >> error do most likely it was EOF ). I didnt follow the second part. > > I think probably it got -ENODEV, looking at kernfs_file_read_iter(). > >> If the file descriptor read returns EOF, even if we consider them >> separate how will it resolve this issue? >> >> My earlier questions were related to fixing it in devcoredump to detect >> and fix it there. Are you suggesting to fix in usermode instead? How? >> > > Yeah, no, you cannot fix it in userspace. > > But I just followed the rabbit hole down kernfs and all, and it looks > like indeed the read would be cut short with -ENODEV, sorry. > > It doesn't look like there's good API for this, but it seems at least > from the underlying kernfs POV it should be possible to get_device() in > open and put_device() in release, so that the device sticks around while > somebody has the file open? It's entirely virtual, so this should be OK? > > johannes Are you suggesting something like below? diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 42dcf96..14203d0 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -32,6 +32,22 @@ static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn) return kobj->ktype ? kobj->ktype->sysfs_ops : NULL; } +static int sysfs_kf_open(struct kernfs_open_file *of) +{ + struct kobject *kobj = of->kn->parent->priv; + struct device *dev = kobj_to_dev(kobj); + + get_device(dev); +} + +static void sysfs_kf_release(struct kernfs_open_file *of) +{ + struct kobject *kobj = of->kn->parent->priv; + struct device *dev = kobj_to_dev(kobj); + + put_device(dev); +} + /* * Reads on sysfs are handled through seq_file, which takes care of hairy * details like buffering and seeking. The following function pipes @@ -211,6 +227,8 @@ static const struct kernfs_ops sysfs_file_kfops_wo = { }; static const struct kernfs_ops sysfs_file_kfops_rw = { + .open = sysfs_kf_open; + .release = sysfs_kf_release; .seq_show = sysfs_kf_seq_show, .write = sysfs_kf_write, }; If so, dont you think this will be a more intrusive change just for the sake of devcoredump? Any other way to keep the changes limited to devcoredump? Thanks Abhinav
WARNING: multiple messages have this Message-ID (diff)
From: Abhinav Kumar <quic_abhinavk@quicinc.com> To: Johannes Berg <johannes@sipsolutions.net>, <linux-kernel@vger.kernel.org> Cc: <rafael@kernel.org>, <linux-arm-msm@vger.kernel.org>, <dri-devel@lists.freedesktop.org>, <swboyd@chromium.org>, <khsieh@codeaurora.org>, <nganji@codeaurora.org>, <seanpaul@chromium.org>, <gregkh@linuxfoundation.org>, <dmitry.baryshkov@linaro.org>, <aravindh@codeaurora.org>, <freedreno@lists.freedesktop.org> Subject: Re: [PATCH] devcoredump: increase the device delete timeout to 10 mins Date: Tue, 8 Feb 2022 17:55:18 -0800 [thread overview] Message-ID: <b60d30cf-e435-49c4-a251-b910bc2e94ae@quicinc.com> (raw) In-Reply-To: <c2a6e29063793eecc5c65d32af9d826544404ecc.camel@sipsolutions.net> Hi Johannes On 2/8/2022 1:54 PM, Johannes Berg wrote: > On Tue, 2022-02-08 at 13:40 -0800, Abhinav Kumar wrote: >>> >> I am checking what usermode sees and will get back ( I didnt see an >> error do most likely it was EOF ). I didnt follow the second part. > > I think probably it got -ENODEV, looking at kernfs_file_read_iter(). > >> If the file descriptor read returns EOF, even if we consider them >> separate how will it resolve this issue? >> >> My earlier questions were related to fixing it in devcoredump to detect >> and fix it there. Are you suggesting to fix in usermode instead? How? >> > > Yeah, no, you cannot fix it in userspace. > > But I just followed the rabbit hole down kernfs and all, and it looks > like indeed the read would be cut short with -ENODEV, sorry. > > It doesn't look like there's good API for this, but it seems at least > from the underlying kernfs POV it should be possible to get_device() in > open and put_device() in release, so that the device sticks around while > somebody has the file open? It's entirely virtual, so this should be OK? > > johannes Are you suggesting something like below? diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 42dcf96..14203d0 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -32,6 +32,22 @@ static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn) return kobj->ktype ? kobj->ktype->sysfs_ops : NULL; } +static int sysfs_kf_open(struct kernfs_open_file *of) +{ + struct kobject *kobj = of->kn->parent->priv; + struct device *dev = kobj_to_dev(kobj); + + get_device(dev); +} + +static void sysfs_kf_release(struct kernfs_open_file *of) +{ + struct kobject *kobj = of->kn->parent->priv; + struct device *dev = kobj_to_dev(kobj); + + put_device(dev); +} + /* * Reads on sysfs are handled through seq_file, which takes care of hairy * details like buffering and seeking. The following function pipes @@ -211,6 +227,8 @@ static const struct kernfs_ops sysfs_file_kfops_wo = { }; static const struct kernfs_ops sysfs_file_kfops_rw = { + .open = sysfs_kf_open; + .release = sysfs_kf_release; .seq_show = sysfs_kf_seq_show, .write = sysfs_kf_write, }; If so, dont you think this will be a more intrusive change just for the sake of devcoredump? Any other way to keep the changes limited to devcoredump? Thanks Abhinav
next prev parent reply other threads:[~2022-02-09 1:55 UTC|newest] Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-02-08 19:44 [PATCH] devcoredump: increase the device delete timeout to 10 mins Abhinav Kumar 2022-02-08 19:44 ` Abhinav Kumar 2022-02-08 20:35 ` Johannes Berg 2022-02-08 20:35 ` Johannes Berg 2022-02-08 21:04 ` Abhinav Kumar 2022-02-08 21:04 ` Abhinav Kumar 2022-02-08 21:12 ` Johannes Berg 2022-02-08 21:12 ` Johannes Berg 2022-02-08 21:40 ` Abhinav Kumar 2022-02-08 21:40 ` Abhinav Kumar 2022-02-08 21:54 ` Johannes Berg 2022-02-09 1:55 ` Abhinav Kumar [this message] 2022-02-09 1:55 ` Abhinav Kumar 2022-02-09 7:50 ` Johannes Berg 2022-02-09 16:29 ` Abhinav Kumar 2022-02-09 16:29 ` Abhinav Kumar 2022-02-11 11:09 ` Greg KH 2022-02-11 11:09 ` Greg KH 2022-02-11 11:09 ` Greg KH 2022-02-11 11:09 ` Greg KH 2022-02-11 18:59 ` Abhinav Kumar 2022-02-11 18:59 ` Abhinav Kumar 2022-02-12 7:04 ` Greg KH 2022-02-12 7:04 ` Greg KH 2022-02-12 7:52 ` Abhinav Kumar 2022-02-12 7:52 ` Abhinav Kumar 2022-02-12 8:24 ` Johannes Berg 2022-02-12 8:24 ` Johannes Berg 2022-02-12 8:35 ` Abhinav Kumar 2022-02-12 8:35 ` Abhinav Kumar 2022-02-28 21:38 ` Abhinav Kumar 2022-02-28 21:38 ` Abhinav Kumar 2022-03-01 6:48 ` David Laight 2022-03-01 17:45 ` Rob Clark 2022-03-01 17:45 ` Rob Clark 2022-03-11 11:53 ` Johannes Berg 2022-03-11 11:53 ` Johannes Berg 2022-02-12 8:29 ` Greg KH 2022-02-12 8:29 ` Greg KH 2022-02-12 8:33 ` Abhinav Kumar 2022-02-12 8:33 ` Abhinav Kumar
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