[RHEL8,COMMIT] userfaultfd: selftest: generalize read and poll

Submitted by Konstantin Khorenko on April 20, 2020, 7:34 a.m.

Details

Message ID 202004200734.03K7Yq4d017218@finist_co8.work.ct
State New
Series "Series without cover letter"
Headers show

Commit Message

Konstantin Khorenko April 20, 2020, 7:34 a.m.
The commit is pushed to "branch-rh8-4.18.0-80.1.2.vz8.3.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-80.1.2.vz8.3.6
------>
commit 03e38924ed14aff7e4c15e210d711e3a17c7588a
Author: Peter Xu <peterx@redhat.com>
Date:   Mon Apr 20 10:34:51 2020 +0300

    userfaultfd: selftest: generalize read and poll
    
    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@redhat.com>
    Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
    Cc: Shuah Khan <shuah@kernel.org>
    Cc: Mike Kravetz <mike.kravetz@oracle.com>
    Cc: Jerome Glisse <jglisse@redhat.com>
    Cc: Zi Yan <zi.yan@cs.rutgers.edu>
    Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
    Cc: Shaohua Li <shli@fb.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-102938
    (cherry picked from commit 04d877319e2aa3895cc7998adb32de0967d3927b)
    Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 tools/testing/selftests/vm/userfaultfd.c | 77 ++++++++++++++++++--------------
 1 file changed, 43 insertions(+), 34 deletions(-)

Patch hide | download patch | download mbox

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;
 }