git: cb01cc4a1020 - main - linux(4): Replace copyin() by fueword32() in handle_futex_death().

[Dmitry Chagin]

The branch main has been updated by dchagin:

URL: https://cgit.FreeBSD.org/src/commit/?id=cb01cc4a1020d7916bcf0f1e774156745c387409

commit cb01cc4a1020d7916bcf0f1e774156745c387409
Author:     Dmitry Chagin <dchagin at FreeBSD.org>
AuthorDate: 2021-07-29 09:48:59 +0000
Commit:     Dmitry Chagin <dchagin at FreeBSD.org>
CommitDate: 2021-07-29 09:48:59 +0000

    linux(4): Replace copyin() by fueword32() in handle_futex_death().
    
    According to fetch(9) fueword facility designed to fetch atomically
    small amount of data from user space.
    
    Reviewed by:            kib
    Differential Revision:  https://reviews.freebsd.org/D31239
    MFC after:              2 weeks
---
 sys/compat/linux/linux_futex.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/sys/compat/linux/linux_futex.c b/sys/compat/linux/linux_futex.c
index df6c7cdbf74a..9dab78a75af2 100644
--- a/sys/compat/linux/linux_futex.c
+++ b/sys/compat/linux/linux_futex.c
@@ -101,7 +101,6 @@ LIN_SDT_PROBE_DEFINE0(futex, linux_futex, unimplemented_cmp_requeue_pi);
 LIN_SDT_PROBE_DEFINE1(futex, linux_futex, unknown_operation, "int");
 LIN_SDT_PROBE_DEFINE0(futex, linux_set_robust_list, size_error);
 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, copyout_error, "int");
-LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, copyin_error, "int");
 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, copyin_error, "int");
 LIN_SDT_PROBE_DEFINE1(futex, release_futexes, copyin_error, "int");
 
@@ -705,11 +704,9 @@ handle_futex_death(struct linux_emuldata *em, uint32_t *uaddr,
 	int error;
 
 retry:
-	error = copyin(uaddr, &uval, 4);
-	if (error) {
-		LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error);
+	error = fueword32(uaddr, &uval);
+	if (error != 0)
 		return (EFAULT);
-	}
 	if ((uval & FUTEX_TID_MASK) == em->em_tid) {
 		mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
 		nval = casuword32(uaddr, uval, mval);