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authorArnd Bergmann <arnd@arndb.de>2021-08-11 08:30:22 +0100
committerRussell King (Oracle) <rmk+kernel@armlinux.org.uk>2021-08-20 11:39:26 +0100
commit249dbe74d3c4b568a623fb55c56cddf19fdf0b89 (patch)
treefd5589c73ebae8ca985846b0cf07508d5a82ca9a /fs
parent4e57a4ddf6b0d9cce1cf2ffd153df1ad3c2c9cc2 (diff)
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ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation
The epoll_wait() system call wrapper is one of the remaining users of the set_fs() infrasturcture for Arm. Changing it to not require set_fs() is rather complex unfortunately. The approach I'm taking here is to allow architectures to override the code that copies the output to user space, and let the oabi-compat implementation check whether it is getting called from an EABI or OABI system call based on the thread_info->syscall value. The in_oabi_syscall() check here mirrors the in_compat_syscall() and in_x32_syscall() helpers for 32-bit compat implementations on other architectures. Overall, the amount of code goes down, at least with the newly added sys_oabi_epoll_pwait() helper getting removed again. The downside is added complexity in the source code for the native implementation. There should be no difference in runtime performance except for Arm kernels with CONFIG_OABI_COMPAT enabled that now have to go through an external function call to check which of the two variants to use. Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/eventpoll.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 1e596e1d0bba..c90c4352325e 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1684,8 +1684,8 @@ static int ep_send_events(struct eventpoll *ep,
if (!revents)
continue;
- if (__put_user(revents, &events->events) ||
- __put_user(epi->event.data, &events->data)) {
+ events = epoll_put_uevent(revents, epi->event.data, events);
+ if (!events) {
list_add(&epi->rdllink, &txlist);
ep_pm_stay_awake(epi);
if (!res)
@@ -1693,7 +1693,6 @@ static int ep_send_events(struct eventpoll *ep,
break;
}
res++;
- events++;
if (epi->event.events & EPOLLONESHOT)
epi->event.events &= EP_PRIVATE_BITS;
else if (!(epi->event.events & EPOLLET)) {