From: Dan Williams <dan.j.williams@intel.com> To: gregkh@linuxfoundation.org Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>, Alexander Viro <viro@zeniv.linux.org.uk>, logang@deltatee.com, Hans Verkuil <hans.verkuil@cisco.com>, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org Subject: [PATCH 0/3] cdev: Generic shutdown handling Date: Wed, 20 Jan 2021 11:38:52 -0800 [thread overview] Message-ID: <161117153248.2853729.2452425259045172318.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) After reviewing driver submissions with new cdev + ioctl usages one common stumbling block is coordinating the shutdown of the ioctl path, or other file operations, at driver ->remove() time. While cdev_del() guarantees that no new file descriptors will be established, operations on existing file descriptors can proceed indefinitely. Given the observation that the kernel spends the resources for a percpu_ref per request_queue shared with all block_devices on a gendisk, do the same for all the cdev instances that share the same cdev_add()-to-cdev_del() lifetime. With this in place cdev_del() not only guarantees 'no new opens', but it also guarantees 'no new operations invocations' and 'all threads running in an operation handler have exited that handler'. As a proof point of the way driver implementations open-code around this gap in the api the libnvdimm ioctl path is reworked with a result of: 4 files changed, 101 insertions(+), 153 deletions(-) --- Dan Williams (3): cdev: Finish the cdev api with queued mode support libnvdimm/ida: Switch to non-deprecated ida helpers libnvdimm/ioctl: Switch to cdev_register_queued() drivers/nvdimm/btt_devs.c | 6 + drivers/nvdimm/bus.c | 177 +++++++++------------------------------ drivers/nvdimm/core.c | 14 ++- drivers/nvdimm/dax_devs.c | 4 - drivers/nvdimm/dimm_devs.c | 53 +++++++++--- drivers/nvdimm/namespace_devs.c | 14 +-- drivers/nvdimm/nd-core.h | 14 ++- drivers/nvdimm/pfn_devs.c | 4 - fs/char_dev.c | 108 ++++++++++++++++++++++-- include/linux/cdev.h | 21 ++++- 10 files changed, 238 insertions(+), 177 deletions(-) _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com> To: gregkh@linuxfoundation.org Cc: Ira Weiny <ira.weiny@intel.com>, Dave Jiang <dave.jiang@intel.com>, Alexandre Belloni <alexandre.belloni@free-electrons.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Vishal Verma <vishal.l.verma@intel.com>, Logan Gunthorpe <logang@deltatee.com>, Hans Verkuil <hans.verkuil@cisco.com>, logang@deltatee.com, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org Subject: [PATCH 0/3] cdev: Generic shutdown handling Date: Wed, 20 Jan 2021 11:38:52 -0800 [thread overview] Message-ID: <161117153248.2853729.2452425259045172318.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) After reviewing driver submissions with new cdev + ioctl usages one common stumbling block is coordinating the shutdown of the ioctl path, or other file operations, at driver ->remove() time. While cdev_del() guarantees that no new file descriptors will be established, operations on existing file descriptors can proceed indefinitely. Given the observation that the kernel spends the resources for a percpu_ref per request_queue shared with all block_devices on a gendisk, do the same for all the cdev instances that share the same cdev_add()-to-cdev_del() lifetime. With this in place cdev_del() not only guarantees 'no new opens', but it also guarantees 'no new operations invocations' and 'all threads running in an operation handler have exited that handler'. As a proof point of the way driver implementations open-code around this gap in the api the libnvdimm ioctl path is reworked with a result of: 4 files changed, 101 insertions(+), 153 deletions(-) --- Dan Williams (3): cdev: Finish the cdev api with queued mode support libnvdimm/ida: Switch to non-deprecated ida helpers libnvdimm/ioctl: Switch to cdev_register_queued() drivers/nvdimm/btt_devs.c | 6 + drivers/nvdimm/bus.c | 177 +++++++++------------------------------ drivers/nvdimm/core.c | 14 ++- drivers/nvdimm/dax_devs.c | 4 - drivers/nvdimm/dimm_devs.c | 53 +++++++++--- drivers/nvdimm/namespace_devs.c | 14 +-- drivers/nvdimm/nd-core.h | 14 ++- drivers/nvdimm/pfn_devs.c | 4 - fs/char_dev.c | 108 ++++++++++++++++++++++-- include/linux/cdev.h | 21 ++++- 10 files changed, 238 insertions(+), 177 deletions(-)
next reply other threads:[~2021-01-20 19:38 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-20 19:38 Dan Williams [this message] 2021-01-20 19:38 ` [PATCH 0/3] cdev: Generic shutdown handling Dan Williams 2021-01-20 19:38 ` [PATCH 1/3] cdev: Finish the cdev api with queued mode support Dan Williams 2021-01-20 19:38 ` Dan Williams 2021-01-20 19:46 ` Christoph Hellwig 2021-01-20 19:46 ` Christoph Hellwig 2021-01-20 20:20 ` Dan Williams 2021-01-20 20:20 ` Dan Williams 2021-01-20 21:39 ` Dan Williams 2021-01-20 21:39 ` Dan Williams 2021-01-20 19:50 ` Logan Gunthorpe 2021-01-20 19:50 ` Logan Gunthorpe 2021-01-20 20:38 ` Dan Williams 2021-01-20 20:38 ` Dan Williams 2021-01-21 8:13 ` Greg KH 2021-01-21 8:13 ` Greg KH 2021-01-21 17:50 ` Dan Williams 2021-01-21 17:50 ` Dan Williams 2021-01-20 19:39 ` [PATCH 2/3] libnvdimm/ida: Switch to non-deprecated ida helpers Dan Williams 2021-01-20 19:39 ` Dan Williams 2021-01-20 19:39 ` [PATCH 3/3] libnvdimm/ioctl: Switch to cdev_register_queued() Dan Williams 2021-01-20 19:39 ` Dan Williams 2021-01-21 8:15 ` Greg KH 2021-01-21 8:15 ` Greg KH 2021-01-21 17:02 ` Dan Williams 2021-01-21 17:02 ` Dan Williams 2021-01-30 1:59 ` [PATCH 0/3] cdev: Generic shutdown handling Dan Williams 2021-01-30 1:59 ` Dan Williams
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=161117153248.2853729.2452425259045172318.stgit@dwillia2-desk3.amr.corp.intel.com \ --to=dan.j.williams@intel.com \ --cc=alexandre.belloni@free-electrons.com \ --cc=gregkh@linuxfoundation.org \ --cc=hans.verkuil@cisco.com \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-nvdimm@lists.01.org \ --cc=logang@deltatee.com \ --cc=viro@zeniv.linux.org.uk \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.