[PATCH RFC v3 4/7] epoll: Add implementation for epoll_ctl_batch

Fam Zheng
2015-02-13T09:06:29Z

This new syscall is a batched version of epoll_ctl. It will execute each
command as specified in cmds in given order, and stop at first failure
or upon completion of all commands.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
fs/eventpoll.c | 48 ++++++++++++++++++++++++++++++++++++++++++
include/linux/syscalls.h | 4 ++++
include/uapi/linux/eventpoll.h | 11 ++++++++++
3 files changed, 63 insertions(+)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 6a2b0a4..12e2e63 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2069,6 +2069,54 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
sigmask ? &ksigmask : NULL);
}

+SYSCALL_DEFINE4(epoll_ctl_batch, int, epfd, int, flags,
+ int, ncmds, struct epoll_ctl_cmd __user *, cmds)
+{
+ struct epoll_ctl_cmd *kcmds = NULL;
+ int i, r, ret = 0;
+ int cmd_size;
+
+ if (flags)
+ return -EINVAL;
+ if (ncmds <= 0 || !cmds)
+ return -EINVAL;
+ cmd_size = sizeof(struct epoll_ctl_cmd) * ncmds;
+ kcmds = kmalloc(cmd_size, GFP_KERNEL);
+ if (!kcmds)
+ return -ENOMEM;
+ if (copy_from_user(kcmds, cmds, cmd_size)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ for (i = 0; i < ncmds; i++) {
+ struct epoll_event ev = (struct epoll_event) {
+ .events = kcmds[i].events,
+ .data = kcmds[i].data,
+ };
+ if (kcmds[i].flags) {
+ kcmds[i].result = -EINVAL;
+ goto copy;
+ }
+ kcmds[i].result = ep_ctl_do(epfd, kcmds[i].op,
+ kcmds[i].fd, ev);
+ if (kcmds[i].result)
+ goto copy;
+ ret++;
+ }
+copy:
+ r = copy_to_user(cmds, kcmds,
+ sizeof(struct epoll_ctl_cmd) * ncmds);
+ /* Failing to copy the command results back will leave
+ * userspace no way to know the actual error code, but we still
+ * report the number of succeeded commands with ret, so it's
+ * not a big problem. Ignore it for now.
+ */
+ (void) r;
+out:
+ kfree(kcmds);
+ return ret;
+}
+
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
struct epoll_event __user *, events,
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 76d1e38..7d784e3 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -12,6 +12,7 @@
#define _LINUX_SYSCALLS_H

struct epoll_event;
+struct epoll_ctl_cmd;
struct iattr;
struct inode;
struct iocb;
@@ -634,6 +635,9 @@ asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
int maxevents, int timeout,
const sigset_t __user *sigmask,
size_t sigsetsize);
+asmlinkage long sys_epoll_ctl_batch(int epfd, int flags,
+ int ncmds,
+ struct epoll_ctl_cmd __user *cmds);
asmlinkage long sys_gethostname(char __user *name, int len);
asmlinkage long sys_sethostname(char __user *name, int len);
asmlinkage long sys_setdomainname(char __user *name, int len);
diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h
index bc81fb2..4e18b17 100644
--- a/include/uapi/linux/eventpoll.h
+++ b/include/uapi/linux/eventpoll.h
@@ -18,6 +18,8 @@
#include <linux/fcntl.h>
#include <linux/types.h>

+#include <linux/signal.h>
+
/* Flags for epoll_create1. */
#define EPOLL_CLOEXEC O_CLOEXEC

@@ -61,6 +63,15 @@ struct epoll_event {
__u64 data;
} EPOLL_PACKED;

+struct epoll_ctl_cmd {
+ int flags;
+ int op;
+ int fd;
+ __u32 events;
+ __u64 data;
+ int result;
+} EPOLL_PACKED;
+
#ifdef CONFIG_PM_SLEEP
static inline void ep_take_care_of_epollwakeup(struct epoll_event *epev)
{
--
1.9.3