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Kernel: Add fast path to pselect and ppoll 

If events are available right away, don't create epoll object to wait
on. Also fix pselect return value to the number of bits set. Previously
return value could've been greater than that if epoll return EPOLLERR or
EPOLLHUP for events that were not listened to
This commit is contained in:
Bananymous 2025-06-04 17:51:22 +03:00
parent 11174bfa14
commit 448632cf11
1 changed files with 78 additions and 21 deletions
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99
kernel/kernel/Process.cpp
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@ -1595,6 +1595,40 @@ namespace Kernel
arguments.timeout->tv_nsec;
}
{
fd_set rfds, wfds, efds;
FD_ZERO(&rfds);
FD_ZERO(&wfds);
FD_ZERO(&efds);
size_t return_value = 0;
for (int fd = 0; fd < arguments.nfds; fd++)
{
auto inode_or_error = m_open_file_descriptors.inode_of(fd);
if (inode_or_error.is_error())
continue;
auto inode = inode_or_error.release_value();
if (arguments.readfds && FD_ISSET(fd, arguments.readfds) && inode->can_read())
{ FD_SET(fd, &rfds); return_value++; }
if (arguments.writefds && FD_ISSET(fd, arguments.writefds) && inode->can_write())
{ FD_SET(fd, &wfds); return_value++; }
if (arguments.errorfds && FD_ISSET(fd, arguments.errorfds) && inode->has_error())
{ FD_SET(fd, &efds); return_value++; }
}
if (return_value || SystemTimer::get().ns_since_boot() >= waketime_ns)
{
if (arguments.readfds)
memcpy(arguments.readfds, &rfds, sizeof(fd_set));
if (arguments.writefds)
memcpy(arguments.writefds, &wfds, sizeof(fd_set));
if (arguments.errorfds)
memcpy(arguments.errorfds, &efds, sizeof(fd_set));
return return_value;
}
}
auto epoll = TRY(Epoll::create());
for (int fd = 0; fd < arguments.nfds; fd++)
{
@ -1627,18 +1661,19 @@ namespace Kernel
if (arguments.errorfds)
FD_ZERO(arguments.errorfds);
size_t return_value = 0;
for (size_t i = 0; i < waited_events; i++)
{
const int fd = event_buffer[i].data.fd;
if (arguments.readfds && event_buffer[i].events & (EPOLLIN | EPOLLHUP))
FD_SET(fd, arguments.readfds);
{ FD_SET(fd, arguments.readfds); return_value++; }
if (arguments.writefds && event_buffer[i].events & (EPOLLOUT))
FD_SET(fd, arguments.writefds);
{ FD_SET(fd, arguments.writefds); return_value++; }
if (arguments.errorfds && event_buffer[i].events & (EPOLLERR))
FD_SET(fd, arguments.errorfds);
{ FD_SET(fd, arguments.errorfds); return_value++; }
}
return waited_events;
return return_value;
}
BAN::ErrorOr<long> Process::sys_ppoll(pollfd* fds, nfds_t nfds, const timespec* timeout, const sigset_t* sigmask)
@ -1666,14 +1701,48 @@ namespace Kernel
timeout->tv_nsec;
}
uint32_t events_per_fd[OPEN_MAX] {};
size_t return_value = 0;
for (nfds_t i = 0; i < nfds; i++)
{
if (fds[i].fd < 0 || fds[i].fd >= OPEN_MAX)
fds[i].revents = 0;
if (fds[i].fd < 0)
continue;
events_per_fd[fds[i].fd] |= fds[i].events;
auto inode_or_error = m_open_file_descriptors.inode_of(fds[i].fd);
if (inode_or_error.is_error())
{
fds[i].revents |= POLLNVAL;
return_value++;
continue;
}
auto inode = inode_or_error.release_value();
if (inode->has_hungup())
fds[i].revents |= POLLHUP;
if (inode->has_error())
fds[i].revents |= POLLERR;
if ((fds[i].events & (POLLIN | POLLRDNORM)) && inode->can_read())
fds[i].revents |= fds[i].events & (POLLIN | POLLRDNORM);
if ((fds[i].events & (POLLOUT | POLLWRNORM)) && inode->can_write())
fds[i].revents |= fds[i].events & (POLLOUT | POLLWRNORM);
// POLLPRI
// POLLRDBAND
// POLLWRBAND
if (fds[i].revents)
return_value++;
}
if (return_value || SystemTimer::get().ns_since_boot() >= waketime_ns)
return return_value;
uint32_t events_per_fd[OPEN_MAX] {};
for (nfds_t i = 0; i < nfds; i++)
if (fds[i].fd >= 0 && fds[i].fd < OPEN_MAX)
events_per_fd[fds[i].fd] |= fds[i].events;
size_t fd_count = 0;
auto epoll = TRY(Epoll::create());
@ -1682,9 +1751,7 @@ namespace Kernel
if (events_per_fd[fd] == 0)
continue;
auto inode_or_error = m_open_file_descriptors.inode_of(fd);
if (inode_or_error.is_error())
continue;
auto inode = TRY(m_open_file_descriptors.inode_of(fd));
uint32_t events = 0;
if (events_per_fd[fd] & (POLLIN | POLLRDNORM))
@ -1696,7 +1763,7 @@ namespace Kernel
// POLLRDBAND
// POLLWRBAND
TRY(epoll->ctl(EPOLL_CTL_ADD, fd, inode_or_error.release_value(), { .events = events, .data = { .fd = fd }}));
TRY(epoll->ctl(EPOLL_CTL_ADD, fd, inode, { .events = events, .data = { .fd = fd }}));
fd_count++;
}
@ -1706,21 +1773,11 @@ namespace Kernel
const size_t waited_events = TRY(epoll->wait(event_buffer.span(), waketime_ns));
size_t return_value = 0;
for (size_t i = 0; i < nfds; i++)
{
fds[i].revents = 0;
if (fds[i].fd < 0)
continue;
if (m_open_file_descriptors.inode_of(fds[i].fd).is_error())
{
fds[i].revents = POLLNVAL;
return_value++;
continue;
}
for (size_t j = 0; j < waited_events; j++)
{
if (fds[i].fd != event_buffer[j].data.fd)