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-rw-r--r--fs/select.c108
1 files changed, 79 insertions, 29 deletions
diff --git a/fs/select.c b/fs/select.c
index bae321569dfa..35d4adc749d9 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -26,6 +26,9 @@
#include <linux/fs.h>
#include <linux/rcupdate.h>
#include <linux/hrtimer.h>
+#include <linux/sched/rt.h>
+#include <linux/freezer.h>
+#include <net/busy_poll.h>
#include <asm/uaccess.h>
@@ -220,8 +223,7 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
struct poll_table_entry *entry = poll_get_entry(pwq);
if (!entry)
return;
- get_file(filp);
- entry->filp = filp;
+ entry->filp = get_file(filp);
entry->wait_address = wait_address;
entry->key = p->_key;
init_waitqueue_func_entry(&entry->wait, pollwake);
@@ -236,7 +238,8 @@ int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
set_current_state(state);
if (!pwq->triggered)
- rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);
+ rc = freezable_schedule_hrtimeout_range(expires, slack,
+ HRTIMER_MODE_ABS);
__set_current_state(TASK_RUNNING);
/*
@@ -345,8 +348,8 @@ static int max_select_fd(unsigned long n, fd_set_bits *fds)
struct fdtable *fdt;
/* handle last in-complete long-word first */
- set = ~(~0UL << (n & (__NFDBITS-1)));
- n /= __NFDBITS;
+ set = ~(~0UL << (n & (BITS_PER_LONG-1)));
+ n /= BITS_PER_LONG;
fdt = files_fdtable(current->files);
open_fds = fdt->open_fds + n;
max = 0;
@@ -373,7 +376,7 @@ get_max:
max++;
set >>= 1;
} while (set);
- max += n * __NFDBITS;
+ max += n * BITS_PER_LONG;
}
return max;
@@ -384,9 +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)
@@ -400,6 +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);
@@ -422,6 +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;
@@ -429,31 +436,31 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
unsigned long in, out, ex, all_bits, bit = 1, mask, j;
unsigned long res_in = 0, res_out = 0, res_ex = 0;
- const struct file_operations *f_op = NULL;
- struct file *file = NULL;
in = *inp++; out = *outp++; ex = *exp++;
all_bits = in | out | ex;
if (all_bits == 0) {
- i += __NFDBITS;
+ i += BITS_PER_LONG;
continue;
}
- for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
- int fput_needed;
+ for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {
+ struct fd f;
if (i >= n)
break;
if (!(bit & all_bits))
continue;
- file = fget_light(i, &fput_needed);
- if (file) {
- f_op = file->f_op;
+ f = fdget(i);
+ if (f.file) {
+ const struct file_operations *f_op;
+ f_op = f.file->f_op;
mask = DEFAULT_POLLMASK;
if (f_op && f_op->poll) {
- wait_key_set(wait, in, out, bit);
- mask = (*f_op->poll)(file, wait);
+ wait_key_set(wait, in, out,
+ bit, busy_flag);
+ mask = (*f_op->poll)(f.file, wait);
}
- fput_light(file, fput_needed);
+ fdput(f);
if ((mask & POLLIN_SET) && (in & bit)) {
res_in |= bit;
retval++;
@@ -469,6 +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)
@@ -487,6 +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
@@ -718,7 +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;
@@ -726,20 +758,20 @@ static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait)
mask = 0;
fd = pollfd->fd;
if (fd >= 0) {
- int fput_needed;
- struct file * file;
-
- file = fget_light(fd, &fput_needed);
+ struct fd f = fdget(fd);
mask = POLLNVAL;
- if (file != NULL) {
+ if (f.file) {
mask = DEFAULT_POLLMASK;
- if (file->f_op && file->f_op->poll) {
+ if (f.file->f_op && f.file->f_op->poll) {
pwait->_key = pollfd->events|POLLERR|POLLHUP;
- mask = file->f_op->poll(file, pwait);
+ 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;
- fput_light(file, fput_needed);
+ fdput(f);
}
}
pollfd->revents = mask;
@@ -754,6 +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) {
@@ -766,6 +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;
@@ -780,9 +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;
}
}
}
@@ -799,6 +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
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-17 13:48:51 +0000