diff options
Diffstat (limited to 'include/linux/poll.h')
| -rw-r--r-- | include/linux/poll.h | 37 |
1 files changed, 31 insertions, 6 deletions
diff --git a/include/linux/poll.h b/include/linux/poll.h index cf40010ce0cd..48fe8bc398d1 100644 --- a/include/linux/poll.h +++ b/include/linux/poll.h @@ -32,21 +32,46 @@ struct poll_table_struct; */ typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *); +/* + * Do not touch the structure directly, use the access functions + * poll_does_not_wait() and poll_requested_events() instead. + */ typedef struct poll_table_struct { - poll_queue_proc qproc; - unsigned long key; + poll_queue_proc _qproc; + unsigned long _key; } poll_table; static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p) { - if (p && wait_address) - p->qproc(filp, wait_address, p); + if (p && p->_qproc && wait_address) + p->_qproc(filp, wait_address, p); +} + +/* + * Return true if it is guaranteed that poll will not wait. This is the case + * if the poll() of another file descriptor in the set got an event, so there + * is no need for waiting. + */ +static inline bool poll_does_not_wait(const poll_table *p) +{ + return p == NULL || p->_qproc == NULL; +} + +/* + * Return the set of events that the application wants to poll for. + * This is useful for drivers that need to know whether a DMA transfer has + * to be started implicitly on poll(). You typically only want to do that + * if the application is actually polling for POLLIN and/or POLLOUT. + */ +static inline unsigned long poll_requested_events(const poll_table *p) +{ + return p ? p->_key : ~0UL; } static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc) { - pt->qproc = qproc; - pt->key = ~0UL; /* all events enabled */ + pt->_qproc = qproc; + pt->_key = ~0UL; /* all events enabled */ } struct poll_table_entry { |