diff options
Diffstat (limited to 'fs/select.c')
| -rw-r--r-- | fs/select.c | 62 |
1 files changed, 57 insertions, 5 deletions
diff --git a/fs/select.c b/fs/select.c index 6b14dc7df3a4..f9f49c40cfd4 100644 --- a/fs/select.c +++ b/fs/select.c @@ -28,6 +28,7 @@ #include <linux/hrtimer.h> #include <linux/sched/rt.h> #include <linux/freezer.h> +#include <net/ll_poll.h> #include <asm/uaccess.h> @@ -386,9 +387,10 @@ get_max: #define POLLEX_SET (POLLPRI) static inline void wait_key_set(poll_table *wait, unsigned long in, - unsigned long out, unsigned long bit) + unsigned long out, unsigned long bit, + unsigned int ll_flag) { - wait->_key = POLLEX_SET; + wait->_key = POLLEX_SET | ll_flag; if (in & bit) wait->_key |= POLLIN_SET; if (out & bit) @@ -402,6 +404,8 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) poll_table *wait; int retval, i, timed_out = 0; unsigned long slack = 0; + unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; + unsigned long busy_end = 0; rcu_read_lock(); retval = max_select_fd(n, fds); @@ -424,6 +428,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) retval = 0; for (;;) { unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp; + bool can_busy_loop = false; inp = fds->in; outp = fds->out; exp = fds->ex; rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex; @@ -451,7 +456,8 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) f_op = f.file->f_op; mask = DEFAULT_POLLMASK; if (f_op && f_op->poll) { - wait_key_set(wait, in, out, bit); + wait_key_set(wait, in, out, + bit, busy_flag); mask = (*f_op->poll)(f.file, wait); } fdput(f); @@ -470,6 +476,18 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) retval++; wait->_qproc = NULL; } + /* got something, stop busy polling */ + if (retval) { + can_busy_loop = false; + busy_flag = 0; + + /* + * only remember a returned + * POLL_BUSY_LOOP if we asked for it + */ + } else if (busy_flag & mask) + can_busy_loop = true; + } } if (res_in) @@ -488,6 +506,17 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) break; } + /* only if found POLL_BUSY_LOOP sockets && not out of time */ + if (can_busy_loop && !need_resched()) { + if (!busy_end) { + busy_end = busy_loop_end_time(); + continue; + } + if (!busy_loop_timeout(busy_end)) + continue; + } + busy_flag = 0; + /* * If this is the first loop and we have a timeout * given, then we convert to ktime_t and set the to @@ -719,7 +748,9 @@ struct poll_list { * pwait poll_table will be used by the fd-provided poll handler for waiting, * if pwait->_qproc is non-NULL. */ -static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait) +static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait, + bool *can_busy_poll, + unsigned int busy_flag) { unsigned int mask; int fd; @@ -733,7 +764,10 @@ static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait) mask = DEFAULT_POLLMASK; if (f.file->f_op && f.file->f_op->poll) { pwait->_key = pollfd->events|POLLERR|POLLHUP; + pwait->_key |= busy_flag; mask = f.file->f_op->poll(f.file, pwait); + if (mask & busy_flag) + *can_busy_poll = true; } /* Mask out unneeded events. */ mask &= pollfd->events | POLLERR | POLLHUP; @@ -752,6 +786,8 @@ static int do_poll(unsigned int nfds, struct poll_list *list, ktime_t expire, *to = NULL; int timed_out = 0, count = 0; unsigned long slack = 0; + unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; + unsigned long busy_end = 0; /* Optimise the no-wait case */ if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { @@ -764,6 +800,7 @@ static int do_poll(unsigned int nfds, struct poll_list *list, for (;;) { struct poll_list *walk; + bool can_busy_loop = false; for (walk = list; walk != NULL; walk = walk->next) { struct pollfd * pfd, * pfd_end; @@ -778,9 +815,13 @@ static int do_poll(unsigned int nfds, struct poll_list *list, * this. They'll get immediately deregistered * when we break out and return. */ - if (do_pollfd(pfd, pt)) { + if (do_pollfd(pfd, pt, &can_busy_loop, + busy_flag)) { count++; pt->_qproc = NULL; + /* found something, stop busy polling */ + busy_flag = 0; + can_busy_loop = false; } } } @@ -797,6 +838,17 @@ static int do_poll(unsigned int nfds, struct poll_list *list, if (count || timed_out) break; + /* only if found POLL_BUSY_LOOP sockets && not out of time */ + if (can_busy_loop && !need_resched()) { + if (!busy_end) { + busy_end = busy_loop_end_time(); + continue; + } + if (!busy_loop_timeout(busy_end)) + continue; + } + busy_flag = 0; + /* * If this is the first loop and we have a timeout * given, then we convert to ktime_t and set the to |