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-rw-r--r--fs/select.c86
1 files changed, 40 insertions, 46 deletions
diff --git a/fs/select.c b/fs/select.c
index 0ee55af1a55c..7da531b1cf6b 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -77,19 +77,16 @@ u64 select_estimate_accuracy(struct timespec64 *tv)
{
u64 ret;
struct timespec64 now;
+ u64 slack = current->timer_slack_ns;
- /*
- * Realtime tasks get a slack of 0 for obvious reasons.
- */
-
- if (rt_task(current))
+ if (slack == 0)
return 0;
ktime_get_ts64(&now);
now = timespec64_sub(*tv, now);
ret = __estimate_accuracy(&now);
- if (ret < current->timer_slack_ns)
- return current->timer_slack_ns;
+ if (ret < slack)
+ return slack;
return ret;
}
@@ -465,18 +462,25 @@ get_max:
EPOLLNVAL)
#define POLLEX_SET (EPOLLPRI | EPOLLNVAL)
-static inline void wait_key_set(poll_table *wait, unsigned long in,
+static inline __poll_t select_poll_one(int fd, poll_table *wait, unsigned long in,
unsigned long out, unsigned long bit,
__poll_t ll_flag)
{
+ CLASS(fd, f)(fd);
+
+ if (fd_empty(f))
+ return EPOLLNVAL;
+
wait->_key = POLLEX_SET | ll_flag;
if (in & bit)
wait->_key |= POLLIN_SET;
if (out & bit)
wait->_key |= POLLOUT_SET;
+
+ return vfs_poll(fd_file(f), wait);
}
-static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
+static noinline_for_stack int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
{
ktime_t expire, *to = NULL;
struct poll_wqueues table;
@@ -525,20 +529,12 @@ static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
}
for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {
- struct fd f;
if (i >= n)
break;
if (!(bit & all_bits))
continue;
- mask = EPOLLNVAL;
- f = fdget(i);
- if (f.file) {
- wait_key_set(wait, in, out, bit,
- busy_flag);
- mask = vfs_poll(f.file, wait);
-
- fdput(f);
- }
+ mask = select_poll_one(i, wait, in, out, bit,
+ busy_flag);
if ((mask & POLLIN_SET) && (in & bit)) {
res_in |= bit;
retval++;
@@ -780,7 +776,9 @@ static inline int get_sigset_argpack(struct sigset_argpack *to,
{
// the path is hot enough for overhead of copy_from_user() to matter
if (from) {
- if (!user_read_access_begin(from, sizeof(*from)))
+ if (can_do_masked_user_access())
+ from = masked_user_access_begin(from);
+ else if (!user_read_access_begin(from, sizeof(*from)))
return -EFAULT;
unsafe_get_user(to->p, &from->p, Efault);
unsafe_get_user(to->size, &from->size, Efault);
@@ -788,7 +786,7 @@ static inline int get_sigset_argpack(struct sigset_argpack *to,
}
return 0;
Efault:
- user_access_end();
+ user_read_access_end();
return -EFAULT;
}
@@ -839,8 +837,8 @@ SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
struct poll_list {
struct poll_list *next;
- int len;
- struct pollfd entries[];
+ unsigned int len;
+ struct pollfd entries[] __counted_by(len);
};
#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
@@ -857,29 +855,22 @@ static inline __poll_t do_pollfd(struct pollfd *pollfd, poll_table *pwait,
__poll_t busy_flag)
{
int fd = pollfd->fd;
- __poll_t mask = 0, filter;
- struct fd f;
+ __poll_t mask, filter;
if (fd < 0)
- goto out;
- mask = EPOLLNVAL;
- f = fdget(fd);
- if (!f.file)
- goto out;
+ return 0;
+
+ CLASS(fd, f)(fd);
+ if (fd_empty(f))
+ return EPOLLNVAL;
/* userland u16 ->events contains POLL... bitmap */
filter = demangle_poll(pollfd->events) | EPOLLERR | EPOLLHUP;
pwait->_key = filter | busy_flag;
- mask = vfs_poll(f.file, pwait);
+ mask = vfs_poll(fd_file(f), pwait);
if (mask & busy_flag)
*can_busy_poll = true;
- mask &= filter; /* Mask out unneeded events. */
- fdput(f);
-
-out:
- /* ... and so does ->revents */
- pollfd->revents = mangle_poll(mask);
- return mask;
+ return mask & filter; /* Mask out unneeded events. */
}
static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
@@ -911,6 +902,7 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
pfd = walk->entries;
pfd_end = pfd + walk->len;
for (; pfd != pfd_end; pfd++) {
+ __poll_t mask;
/*
* Fish for events. If we found one, record it
* and kill poll_table->_qproc, so we don't
@@ -918,8 +910,9 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
* this. They'll get immediately deregistered
* when we break out and return.
*/
- if (do_pollfd(pfd, pt, &can_busy_loop,
- busy_flag)) {
+ mask = do_pollfd(pfd, pt, &can_busy_loop, busy_flag);
+ pfd->revents = mangle_poll(mask);
+ if (mask) {
count++;
pt->_qproc = NULL;
/* found something, stop busy polling */
@@ -975,14 +968,15 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
struct timespec64 *end_time)
{
struct poll_wqueues table;
- int err = -EFAULT, fdcount, len;
+ int err = -EFAULT, fdcount;
/* Allocate small arguments on the stack to save memory and be
faster - use long to make sure the buffer is aligned properly
on 64 bit archs to avoid unaligned access */
long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
struct poll_list *const head = (struct poll_list *)stack_pps;
struct poll_list *walk = head;
- unsigned long todo = nfds;
+ unsigned int todo = nfds;
+ unsigned int len;
if (nfds > rlimit(RLIMIT_NOFILE))
return -EINVAL;
@@ -998,9 +992,9 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
sizeof(struct pollfd) * walk->len))
goto out_fds;
- todo -= walk->len;
- if (!todo)
+ if (walk->len >= todo)
break;
+ todo -= walk->len;
len = min(todo, POLLFD_PER_PAGE);
walk = walk->next = kmalloc(struct_size(walk, entries, len),
@@ -1020,7 +1014,7 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
for (walk = head; walk; walk = walk->next) {
struct pollfd *fds = walk->entries;
- int j;
+ unsigned int j;
for (j = walk->len; j; fds++, ufds++, j--)
unsafe_put_user(fds->revents, &ufds->revents, Efault);
@@ -1361,7 +1355,7 @@ static inline int get_compat_sigset_argpack(struct compat_sigset_argpack *to,
}
return 0;
Efault:
- user_access_end();
+ user_read_access_end();
return -EFAULT;
}
generated by cgit (git 2.34.1) at 2025-07-25 17:40:11 +0000