From: Christoph Hellwig <hch@lst.de> To: viro@zeniv.linux.org.uk Cc: Avi Kivity <avi@scylladb.com>, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 05/32] fs: introduce new ->get_poll_head and ->poll_mask methods Date: Fri, 30 Mar 2018 17:07:42 +0200 [thread overview] Message-ID: <20180330150809.28094-6-hch@lst.de> (raw) In-Reply-To: <20180330150809.28094-1-hch@lst.de> ->get_poll_head returns the waitqueue that the poll operation is going to sleep on. Note that this means we can only use a single waitqueue for the poll, unlike some current drivers that use two waitqueues for different events. But now that we have keyed wakeups and heavily use those for poll there aren't that many good reason left to keep the multiple waitqueues, and if there are any ->poll is still around, the driver just won't support aio poll. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --- Documentation/filesystems/Locking | 7 ++++++- Documentation/filesystems/vfs.txt | 13 +++++++++++++ fs/select.c | 28 ++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ include/linux/poll.h | 27 +++++++++++++++++++++++---- 5 files changed, 72 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 220bba28f72b..6d227f9d7bd9 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -440,6 +440,8 @@ prototypes: ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); int (*iterate) (struct file *, struct dir_context *); __poll_t (*poll) (struct file *, struct poll_table_struct *); + struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t); + __poll_t (*poll_mask) (struct file *, __poll_t); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); @@ -470,7 +472,7 @@ prototypes: }; locking rules: - All may block. + All except for ->poll_mask may block. ->llseek() locking has moved from llseek to the individual llseek implementations. If your fs is not using generic_file_llseek, you @@ -498,6 +500,9 @@ in sys_read() and friends. the lease within the individual filesystem to record the result of the operation +->poll_mask can be called with or without the waitqueue lock for the waitqueue +returned from ->get_poll_head. + --------------------------- dquot_operations ------------------------------- prototypes: int (*write_dquot) (struct dquot *); diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index f608180ad59d..50ee13563271 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -857,6 +857,8 @@ struct file_operations { ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); int (*iterate) (struct file *, struct dir_context *); __poll_t (*poll) (struct file *, struct poll_table_struct *); + struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t); + __poll_t (*poll_mask) (struct file *, __poll_t); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); @@ -901,6 +903,17 @@ otherwise noted. activity on this file and (optionally) go to sleep until there is activity. Called by the select(2) and poll(2) system calls + get_poll_head: Returns the struct wait_queue_head that poll, select, + epoll or aio poll should wait on in case this instance only has single + waitqueue. Can return NULL to indicate polling is not supported, + or a POLL* value using the POLL_TO_PTR helper in case a grave error + occured and ->poll_mask shall not be called. + + poll_mask: return the mask of POLL* values describing the file descriptor + state. Called either before going to sleep on the waitqueue returned by + get_poll_head, or after it has been woken. If ->get_poll_head and + ->poll_mask are implemented ->poll does not need to be implement. + unlocked_ioctl: called by the ioctl(2) system call. compat_ioctl: called by the ioctl(2) system call when 32 bit system calls diff --git a/fs/select.c b/fs/select.c index ba91103707ea..cc270d7f6192 100644 --- a/fs/select.c +++ b/fs/select.c @@ -34,6 +34,34 @@ #include <linux/uaccess.h> +__poll_t vfs_poll(struct file *file, struct poll_table_struct *pt) +{ + unsigned int events = poll_requested_events(pt); + struct wait_queue_head *head; + + if (unlikely(!file_can_poll(file))) + return DEFAULT_POLLMASK; + + if (file->f_op->poll) + return file->f_op->poll(file, pt); + + /* + * Only get the poll head and do the first mask check if we are actually + * going to sleep on this file: + */ + if (pt && pt->_qproc) { + head = vfs_get_poll_head(file, events); + if (!head) + return DEFAULT_POLLMASK; + if (IS_ERR(head)) + return PTR_TO_POLL(head); + + pt->_qproc(file, head, pt); + } + + return file->f_op->poll_mask(file, events); +} +EXPORT_SYMBOL_GPL(vfs_poll); /* * Estimate expected accuracy in ns from a timeval. diff --git a/include/linux/fs.h b/include/linux/fs.h index 79c413985305..6ea2c0843bb1 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1708,6 +1708,8 @@ struct file_operations { int (*iterate) (struct file *, struct dir_context *); int (*iterate_shared) (struct file *, struct dir_context *); __poll_t (*poll) (struct file *, struct poll_table_struct *); + struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t); + __poll_t (*poll_mask) (struct file *, __poll_t); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); diff --git a/include/linux/poll.h b/include/linux/poll.h index 7e0fdcf905d2..42e8e8665fb0 100644 --- a/include/linux/poll.h +++ b/include/linux/poll.h @@ -74,18 +74,37 @@ static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) pt->_key = ~(__poll_t)0; /* all events enabled */ } +/* + * ->get_poll_head can return a __poll_t in the PTR_ERR, use these macros + * to return the value and recover it. It takes care of the negation as + * well as off the annotations. + */ +#define POLL_TO_PTR(mask) (ERR_PTR(-(__force int)(mask))) +#define PTR_TO_POLL(ptr) ((__force __poll_t)-PTR_ERR((ptr))) + static inline bool file_can_poll(struct file *file) { - return file->f_op->poll; + return file->f_op->poll || + (file->f_op->get_poll_head && file->f_op->poll_mask); } -static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt) +static inline struct wait_queue_head *vfs_get_poll_head(struct file *file, + __poll_t events) { - if (unlikely(!file->f_op->poll)) + if (unlikely(!file->f_op->get_poll_head || !file->f_op->poll_mask)) + return NULL; + return file->f_op->get_poll_head(file, events); +} + +static inline __poll_t vfs_poll_mask(struct file *file, __poll_t events) +{ + if (unlikely(!file->f_op->poll_mask)) return DEFAULT_POLLMASK; - return file->f_op->poll(file, pt); + return file->f_op->poll_mask(file, events) & events; } +__poll_t vfs_poll(struct file *file, struct poll_table_struct *pt); + struct poll_table_entry { struct file *filp; __poll_t key; -- 2.14.2
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de> To: viro@zeniv.linux.org.uk Cc: Avi Kivity <avi@scylladb.com>, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 05/32] fs: introduce new ->get_poll_head and ->poll_mask methods Date: Fri, 30 Mar 2018 17:07:42 +0200 [thread overview] Message-ID: <20180330150809.28094-6-hch@lst.de> (raw) In-Reply-To: <20180330150809.28094-1-hch@lst.de> ->get_poll_head returns the waitqueue that the poll operation is going to sleep on. Note that this means we can only use a single waitqueue for the poll, unlike some current drivers that use two waitqueues for different events. But now that we have keyed wakeups and heavily use those for poll there aren't that many good reason left to keep the multiple waitqueues, and if there are any ->poll is still around, the driver just won't support aio poll. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --- Documentation/filesystems/Locking | 7 ++++++- Documentation/filesystems/vfs.txt | 13 +++++++++++++ fs/select.c | 28 ++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ include/linux/poll.h | 27 +++++++++++++++++++++++---- 5 files changed, 72 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 220bba28f72b..6d227f9d7bd9 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -440,6 +440,8 @@ prototypes: ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); int (*iterate) (struct file *, struct dir_context *); __poll_t (*poll) (struct file *, struct poll_table_struct *); + struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t); + __poll_t (*poll_mask) (struct file *, __poll_t); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); @@ -470,7 +472,7 @@ prototypes: }; locking rules: - All may block. + All except for ->poll_mask may block. ->llseek() locking has moved from llseek to the individual llseek implementations. If your fs is not using generic_file_llseek, you @@ -498,6 +500,9 @@ in sys_read() and friends. the lease within the individual filesystem to record the result of the operation +->poll_mask can be called with or without the waitqueue lock for the waitqueue +returned from ->get_poll_head. + --------------------------- dquot_operations ------------------------------- prototypes: int (*write_dquot) (struct dquot *); diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index f608180ad59d..50ee13563271 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -857,6 +857,8 @@ struct file_operations { ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); int (*iterate) (struct file *, struct dir_context *); __poll_t (*poll) (struct file *, struct poll_table_struct *); + struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t); + __poll_t (*poll_mask) (struct file *, __poll_t); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); @@ -901,6 +903,17 @@ otherwise noted. activity on this file and (optionally) go to sleep until there is activity. Called by the select(2) and poll(2) system calls + get_poll_head: Returns the struct wait_queue_head that poll, select, + epoll or aio poll should wait on in case this instance only has single + waitqueue. Can return NULL to indicate polling is not supported, + or a POLL* value using the POLL_TO_PTR helper in case a grave error + occured and ->poll_mask shall not be called. + + poll_mask: return the mask of POLL* values describing the file descriptor + state. Called either before going to sleep on the waitqueue returned by + get_poll_head, or after it has been woken. If ->get_poll_head and + ->poll_mask are implemented ->poll does not need to be implement. + unlocked_ioctl: called by the ioctl(2) system call. compat_ioctl: called by the ioctl(2) system call when 32 bit system calls diff --git a/fs/select.c b/fs/select.c index ba91103707ea..cc270d7f6192 100644 --- a/fs/select.c +++ b/fs/select.c @@ -34,6 +34,34 @@ #include <linux/uaccess.h> +__poll_t vfs_poll(struct file *file, struct poll_table_struct *pt) +{ + unsigned int events = poll_requested_events(pt); + struct wait_queue_head *head; + + if (unlikely(!file_can_poll(file))) + return DEFAULT_POLLMASK; + + if (file->f_op->poll) + return file->f_op->poll(file, pt); + + /* + * Only get the poll head and do the first mask check if we are actually + * going to sleep on this file: + */ + if (pt && pt->_qproc) { + head = vfs_get_poll_head(file, events); + if (!head) + return DEFAULT_POLLMASK; + if (IS_ERR(head)) + return PTR_TO_POLL(head); + + pt->_qproc(file, head, pt); + } + + return file->f_op->poll_mask(file, events); +} +EXPORT_SYMBOL_GPL(vfs_poll); /* * Estimate expected accuracy in ns from a timeval. diff --git a/include/linux/fs.h b/include/linux/fs.h index 79c413985305..6ea2c0843bb1 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1708,6 +1708,8 @@ struct file_operations { int (*iterate) (struct file *, struct dir_context *); int (*iterate_shared) (struct file *, struct dir_context *); __poll_t (*poll) (struct file *, struct poll_table_struct *); + struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t); + __poll_t (*poll_mask) (struct file *, __poll_t); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); diff --git a/include/linux/poll.h b/include/linux/poll.h index 7e0fdcf905d2..42e8e8665fb0 100644 --- a/include/linux/poll.h +++ b/include/linux/poll.h @@ -74,18 +74,37 @@ static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) pt->_key = ~(__poll_t)0; /* all events enabled */ } +/* + * ->get_poll_head can return a __poll_t in the PTR_ERR, use these macros + * to return the value and recover it. It takes care of the negation as + * well as off the annotations. + */ +#define POLL_TO_PTR(mask) (ERR_PTR(-(__force int)(mask))) +#define PTR_TO_POLL(ptr) ((__force __poll_t)-PTR_ERR((ptr))) + static inline bool file_can_poll(struct file *file) { - return file->f_op->poll; + return file->f_op->poll || + (file->f_op->get_poll_head && file->f_op->poll_mask); } -static inline __poll_t vfs_poll(struct file *file, struct poll_table_struct *pt) +static inline struct wait_queue_head *vfs_get_poll_head(struct file *file, + __poll_t events) { - if (unlikely(!file->f_op->poll)) + if (unlikely(!file->f_op->get_poll_head || !file->f_op->poll_mask)) + return NULL; + return file->f_op->get_poll_head(file, events); +} + +static inline __poll_t vfs_poll_mask(struct file *file, __poll_t events) +{ + if (unlikely(!file->f_op->poll_mask)) return DEFAULT_POLLMASK; - return file->f_op->poll(file, pt); + return file->f_op->poll_mask(file, events) & events; } +__poll_t vfs_poll(struct file *file, struct poll_table_struct *pt); + struct poll_table_entry { struct file *filp; __poll_t key; -- 2.14.2 -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: <a href=mailto:"aart@kvack.org">aart@kvack.org</a>
next prev parent reply other threads:[~2018-03-30 15:34 UTC|newest] Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-30 15:07 aio poll and a new in-kernel poll API V9 Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 01/32] fs: unexport poll_schedule_timeout Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 02/32] fs: cleanup do_pollfd Christoph Hellwig 2018-03-30 15:07 ` [PATCH 03/32] fs: update documentation to mention __poll_t and match the code Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 04/32] fs: add new vfs_poll and file_can_poll helpers Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig [this message] 2018-03-30 15:07 ` [PATCH 05/32] fs: introduce new ->get_poll_head and ->poll_mask methods Christoph Hellwig 2018-04-06 4:58 ` Al Viro 2018-04-06 4:58 ` Al Viro 2018-03-30 15:07 ` [PATCH 06/32] aio: simplify KIOCB_KEY handling Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 07/32] aio: simplify cancellation Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 08/32] aio: replace kiocb_set_cancel_fn with a cancel_kiocb file operation Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-04-06 2:15 ` Al Viro 2018-04-06 2:15 ` Al Viro 2018-03-30 15:07 ` [PATCH 09/32] aio: add delayed cancel support Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 10/32] aio: implement IOCB_CMD_POLL Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 11/32] net: refactor socket_poll Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 12/32] net: add support for ->poll_mask in proto_ops Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 13/32] net: remove sock_no_poll Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 14/32] net/tcp: convert to ->poll_mask Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 15/32] net/unix: " Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 16/32] net: convert datagram_poll users tp ->poll_mask Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 17/32] net/dccp: convert to ->poll_mask Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 18/32] net/atm: " Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 19/32] net/vmw_vsock: " Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 20/32] net/tipc: " Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 21/32] net/sctp: " Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:07 ` [PATCH 22/32] net/bluetooth: " Christoph Hellwig 2018-03-30 15:07 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 23/32] net/caif: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 24/32] net/nfc: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 25/32] net/phonet: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 26/32] net/iucv: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 27/32] net/rxrpc: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 28/32] crypto: af_alg: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 29/32] pipe: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 30/32] eventfd: switch " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 31/32] timerfd: convert " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-03-30 15:08 ` [PATCH 32/32] random: " Christoph Hellwig 2018-03-30 15:08 ` Christoph Hellwig 2018-05-11 11:07 aio poll and a new in-kernel poll API V10 Christoph Hellwig 2018-05-11 11:07 ` [PATCH 05/32] fs: introduce new ->get_poll_head and ->poll_mask methods Christoph Hellwig 2018-05-15 19:48 aio poll and a new in-kernel poll API V11 Christoph Hellwig 2018-05-15 19:48 ` [PATCH 05/32] fs: introduce new ->get_poll_head and ->poll_mask methods Christoph Hellwig 2018-05-15 19:48 ` Christoph Hellwig
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