From: Peter Xu <peterx at redhat.com>
We do very similar things in read and poll modes, but we're copying the
codes around. Share the codes properly on reading the message and
handling the page fault to make the code cleaner. Meanwhile this solves
previous mismatch of behaviors between the two modes on that the old code:
- did not check EAGAIN case in read() mode
- ignored BOUNCE_VERIFY check in read() mode
Link: http://lkml.kernel.org/r/20180930074259.18229-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx at redhat.com>
Acked-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
Cc: Shuah Khan <shuah at kernel.org>
Cc: Mike Kravetz <mike.kravetz at oracle.com>
Cc: Jerome Glisse <jglisse at redhat.com>
Cc: Zi Yan <zi.yan at cs.rutgers.edu>
Cc: "Kirill A . Shutemov" <kirill at shutemov.name>
Cc: Shaohua Li <shli at fb.com>
Cc: Andrea Arcangeli <aarcange at redhat.com>
Cc: "Dr . David Alan Gilbert" <dgilbert at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
https://jira.sw.ru/browse/PSBM-102938
(cherry picked from commit 04d877319e2aa3895cc7998adb32de0967d3927b)
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
tools/testing/selftests/vm/userfaultfd.c | 77 +++++++++++++-----------
1 file changed, 43 insertions(+), 34 deletions(-)
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 68bbe0eb203e..e987d65b5d43 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -439,6 +439,43 @@ static int copy_page(int ufd, unsigned long offset)
return __copy_page(ufd, offset, false);
}
+static int uffd_read_msg(int ufd, struct uffd_msg *msg)
+{
+ int ret = read(uffd, msg, sizeof(*msg));
+
+ if (ret != sizeof(*msg)) {
+ if (ret < 0) {
+ if (errno == EAGAIN)
+ return 1;
+ else
+ perror("blocking read error"), exit(1);
+ } else {
+ fprintf(stderr, "short read\n"), exit(1);
+ }
+ }
+
+ return 0;
+}
+
+/* Return 1 if page fault handled by us; otherwise 0 */
+static int uffd_handle_page_fault(struct uffd_msg *msg)
+{
+ unsigned long offset;
+
+ if (msg->event != UFFD_EVENT_PAGEFAULT)
+ fprintf(stderr, "unexpected msg event %u\n",
+ msg->event), exit(1);
+
+ if (bounces & BOUNCE_VERIFY &&
+ msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
+ fprintf(stderr, "unexpected write fault\n"), exit(1);
+
+ offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst;
+ offset &= ~(page_size-1);
+
+ return copy_page(uffd, offset);
+}
+
static void *uffd_poll_thread(void *arg)
{
unsigned long cpu = (unsigned long) arg;
@@ -446,7 +483,6 @@ static void *uffd_poll_thread(void *arg)
struct uffd_msg msg;
struct uffdio_register uffd_reg;
int ret;
- unsigned long offset;
char tmp_chr;
unsigned long userfaults = 0;
@@ -470,25 +506,15 @@ static void *uffd_poll_thread(void *arg)
if (!(pollfd[0].revents & POLLIN))
fprintf(stderr, "pollfd[0].revents %d\n",
pollfd[0].revents), exit(1);
- ret = read(uffd, &msg, sizeof(msg));
- if (ret < 0) {
- if (errno == EAGAIN)
- continue;
- perror("nonblocking read error"), exit(1);
- }
+ if (uffd_read_msg(uffd, &msg))
+ continue;
switch (msg.event) {
default:
fprintf(stderr, "unexpected msg event %u\n",
msg.event), exit(1);
break;
case UFFD_EVENT_PAGEFAULT:
- if (msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
- fprintf(stderr, "unexpected write fault\n"), exit(1);
- offset = (char *)(unsigned long)msg.arg.pagefault.address -
- area_dst;
- offset &= ~(page_size-1);
- if (copy_page(uffd, offset))
- userfaults++;
+ userfaults += uffd_handle_page_fault(&msg);
break;
case UFFD_EVENT_FORK:
close(uffd);
@@ -516,8 +542,6 @@ static void *uffd_read_thread(void *arg)
{
unsigned long *this_cpu_userfaults;
struct uffd_msg msg;
- unsigned long offset;
- int ret;
this_cpu_userfaults = (unsigned long *) arg;
*this_cpu_userfaults = 0;
@@ -526,24 +550,9 @@ static void *uffd_read_thread(void *arg)
/* from here cancellation is ok */
for (;;) {
- ret = read(uffd, &msg, sizeof(msg));
- if (ret != sizeof(msg)) {
- if (ret < 0)
- perror("blocking read error"), exit(1);
- else
- fprintf(stderr, "short read\n"), exit(1);
- }
- if (msg.event != UFFD_EVENT_PAGEFAULT)
- fprintf(stderr, "unexpected msg event %u\n",
- msg.event), exit(1);
- if (bounces & BOUNCE_VERIFY &&
- msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
- fprintf(stderr, "unexpected write fault\n"), exit(1);
- offset = (char *)(unsigned long)msg.arg.pagefault.address -
- area_dst;
- offset &= ~(page_size-1);
- if (copy_page(uffd, offset))
- (*this_cpu_userfaults)++;
+ if (uffd_read_msg(uffd, &msg))
+ continue;
+ (*this_cpu_userfaults) += uffd_handle_page_fault(&msg);
}
return (void *)NULL;
}
--
2.25.3