Factor epoll thread
Both ioeventfd and ipc use an epoll thread roughly the same way. In
order to add a new epoll user, factor the common bits into epoll.c
Slight implementation changes which shouldn't affect behavior:
* At the moment ioeventfd mixes file descriptor (for the stop event) and
pointers in the epoll_event.data union, which could in theory cause
aliasing. Use a pointer for the stop event instead. kvm-ipc uses only
file descriptors. It could be changed but since epoll.c compares the
stop event pointer first, the risk of aliasing with an fd is much
lower there.
* kvm-ipc uses EPOLLET, edge-triggered events, but having the stop event
level-triggered shouldn't make a difference.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20230606130426.978945-16-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/kvm-ipc.c b/kvm-ipc.c
index 23f7b12..265d80c 100644
--- a/kvm-ipc.c
+++ b/kvm-ipc.c
@@ -2,9 +2,9 @@
#include <sys/un.h>
#include <sys/types.h>
#include <sys/socket.h>
-#include <sys/eventfd.h>
#include <dirent.h>
+#include "kvm/epoll.h"
#include "kvm/kvm-ipc.h"
#include "kvm/rwsem.h"
#include "kvm/read-write.h"
@@ -28,8 +28,8 @@
extern __thread struct kvm_cpu *current_kvm_cpu;
static void (*msgs[KVM_IPC_MAX_MSGS])(struct kvm *kvm, int fd, u32 type, u32 len, u8 *msg);
static DECLARE_RWSEM(msgs_rwlock);
-static int epoll_fd, server_fd, stop_fd;
-static pthread_t thread;
+static int server_fd;
+static struct kvm__epoll epoll;
static int kvm__create_socket(struct kvm *kvm)
{
@@ -268,7 +268,7 @@
ev.events = EPOLLIN | EPOLLRDHUP;
ev.data.fd = client;
- if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client, &ev) < 0) {
+ if (epoll_ctl(epoll.fd, EPOLL_CTL_ADD, client, &ev) < 0) {
close(client);
return -1;
}
@@ -278,7 +278,7 @@
static void kvm_ipc__close_conn(int fd)
{
- epoll_ctl(epoll_fd, EPOLL_CTL_DEL, fd, NULL);
+ epoll_ctl(epoll.fd, EPOLL_CTL_DEL, fd, NULL);
close(fd);
}
@@ -309,42 +309,26 @@
return -1;
}
-static void *kvm_ipc__thread(void *param)
+static void kvm_ipc__handle_event(struct kvm *kvm, struct epoll_event *ev)
{
- struct epoll_event event;
- struct kvm *kvm = param;
+ int fd = ev->data.fd;
- kvm__set_thread_name("kvm-ipc");
+ if (fd == server_fd) {
+ int client, r;
- for (;;) {
- int nfds;
+ client = kvm_ipc__new_conn(fd);
+ /*
+ * Handle multiple IPC cmd at a time
+ */
+ do {
+ r = kvm_ipc__receive(kvm, client);
+ } while (r == 0);
- nfds = epoll_wait(epoll_fd, &event, 1, -1);
- if (nfds > 0) {
- int fd = event.data.fd;
-
- if (fd == stop_fd && event.events & EPOLLIN) {
- break;
- } else if (fd == server_fd) {
- int client, r;
-
- client = kvm_ipc__new_conn(fd);
- /*
- * Handle multiple IPC cmd at a time
- */
- do {
- r = kvm_ipc__receive(kvm, client);
- } while (r == 0);
-
- } else if (event.events & (EPOLLERR | EPOLLRDHUP | EPOLLHUP)) {
- kvm_ipc__close_conn(fd);
- } else {
- kvm_ipc__receive(kvm, fd);
- }
- }
+ } else if (ev->events & (EPOLLERR | EPOLLRDHUP | EPOLLHUP)) {
+ kvm_ipc__close_conn(fd);
+ } else {
+ kvm_ipc__receive(kvm, fd);
}
-
- return NULL;
}
static void kvm__pid(struct kvm *kvm, int fd, u32 type, u32 len, u8 *msg)
@@ -482,42 +466,21 @@
server_fd = sock;
- epoll_fd = epoll_create(KVM_IPC_MAX_MSGS);
- if (epoll_fd < 0) {
- perror("epoll_create");
- ret = epoll_fd;
+ ret = epoll__init(kvm, &epoll, "kvm-ipc",
+ kvm_ipc__handle_event);
+ if (ret) {
+ pr_err("Failed starting IPC thread");
goto err;
}
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = sock;
- if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock, &ev) < 0) {
+ if (epoll_ctl(epoll.fd, EPOLL_CTL_ADD, sock, &ev) < 0) {
pr_err("Failed adding socket to epoll");
ret = -EFAULT;
goto err_epoll;
}
- stop_fd = eventfd(0, 0);
- if (stop_fd < 0) {
- perror("eventfd");
- ret = stop_fd;
- goto err_epoll;
- }
-
- ev.events = EPOLLIN | EPOLLET;
- ev.data.fd = stop_fd;
- if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, stop_fd, &ev) < 0) {
- pr_err("Failed adding stop event to epoll");
- ret = -EFAULT;
- goto err_stop;
- }
-
- if (pthread_create(&thread, NULL, kvm_ipc__thread, kvm) != 0) {
- pr_err("Failed starting IPC thread");
- ret = -EFAULT;
- goto err_stop;
- }
-
kvm_ipc__register_handler(KVM_IPC_PID, kvm__pid);
kvm_ipc__register_handler(KVM_IPC_DEBUG, handle_debug);
kvm_ipc__register_handler(KVM_IPC_PAUSE, handle_pause);
@@ -528,10 +491,9 @@
return 0;
-err_stop:
- close(stop_fd);
err_epoll:
- close(epoll_fd);
+ epoll__exit(&epoll);
+ close(server_fd);
err:
return ret;
}
@@ -539,18 +501,11 @@
int kvm_ipc__exit(struct kvm *kvm)
{
- u64 val = 1;
- int ret;
-
- ret = write(stop_fd, &val, sizeof(val));
- if (ret < 0)
- return ret;
-
+ epoll__exit(&epoll);
close(server_fd);
- close(epoll_fd);
kvm__remove_socket(kvm->cfg.guest_name);
- return ret;
+ return 0;
}
base_exit(kvm_ipc__exit);
