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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>
This commit is contained in:
Peter Xu 2018-10-26 15:09:13 -07:00 committed by Linus Torvalds
parent 439de0d744
commit 04d877319e
1 changed files with 43 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
tools/testing/selftests/vm/userfaultfd.c
View File

@ -451,6 +451,43 @@ 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;
@ -458,7 +495,6 @@ 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;
@ -482,25 +518,15 @@ 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);
@ -528,8 +554,6 @@ 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;
@ -538,24 +562,9 @@ 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;
}