Merge tag 'riscv-mw1-6.16-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/alexghiti/linux into for-next

riscv patches for 6.16-rc1

* Implement atomic patching support for ftrace which finally allows to
  get rid of stop_machine().
* Support for kexec_file_load() syscall
* Improve module loading time by changing the algorithm that counts the
  number of plt/got entries in a module.
* Zicbop is now used in the kernel to prefetch instructions

[Palmer: There's been two rounds of surgery on this one, so as a result
it's a bit different than the PR.]

* alex-pr: (734 commits)
  riscv: Improve Kconfig help for RISCV_ISA_V_PREEMPTIVE
  MAINTAINERS: Update Atish's email address
  riscv: hwprobe: export Zabha extension
  riscv: Make regs_irqs_disabled() more clear
  perf symbols: Ignore mapping symbols on riscv
  RISC-V: Kconfig: Fix help text of CMDLINE_EXTEND
  riscv: module: Optimize PLT/GOT entry counting
  riscv: Add support for PUD THP
  riscv: xchg: Prefetch the destination word for sc.w
  riscv: Add ARCH_HAS_PREFETCH[W] support with Zicbop
  riscv: Add support for Zicbop
  riscv: Introduce Zicbop instructions
  riscv/kexec_file: Fix comment in purgatory relocator
  riscv: kexec_file: Support loading Image binary file
  riscv: kexec_file: Split the loading of kernel and others
  riscv: Documentation: add a description about dynamic ftrace
  riscv: ftrace: support direct call using call_ops
  riscv: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
  riscv: ftrace: support PREEMPT
  riscv: add a data fence for CMODX in the kernel mode
  ...

Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>

1 files changed, 21 insertions, 13 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 14935a0500a2..d9ca80dcc544 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1830,6 +1830,8 @@ static inline void namespace_lock(void)
 	down_write(&namespace_sem);
 }
 
+DEFINE_GUARD(namespace_lock, struct rw_semaphore *, namespace_lock(), namespace_unlock())
+
 enum umount_tree_flags {
 	UMOUNT_SYNC = 1,
 	UMOUNT_PROPAGATE = 2,
@@ -2383,7 +2385,7 @@ void dissolve_on_fput(struct vfsmount *mnt)
 			return;
 	}
 
-	scoped_guard(rwsem_write, &namespace_sem) {
+	scoped_guard(namespace_lock, &namespace_sem) {
 		ns = m->mnt_ns;
 		if (!must_dissolve(ns))
 			return;
@@ -5189,8 +5191,8 @@ static void finish_mount_kattr(struct mount_kattr *kattr)
 		mnt_idmap_put(kattr->mnt_idmap);
 }
 
-static int copy_mount_setattr(struct mount_attr __user *uattr, size_t usize,
-			      struct mount_kattr *kattr)
+static int wants_mount_setattr(struct mount_attr __user *uattr, size_t usize,
+			       struct mount_kattr *kattr)
 {
 	int ret;
 	struct mount_attr attr;
@@ -5213,9 +5215,13 @@ static int copy_mount_setattr(struct mount_attr __user *uattr, size_t usize,
 	if (attr.attr_set == 0 &&
 	    attr.attr_clr == 0 &&
 	    attr.propagation == 0)
-		return 0;
+		return 0; /* Tell caller to not bother. */
+
+	ret = build_mount_kattr(&attr, usize, kattr);
+	if (ret < 0)
+		return ret;
 
-	return build_mount_kattr(&attr, usize, kattr);
+	return 1;
 }
 
 SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
@@ -5247,8 +5253,8 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
 	if (flags & AT_RECURSIVE)
 		kattr.kflags |= MOUNT_KATTR_RECURSE;
 
-	err = copy_mount_setattr(uattr, usize, &kattr);
-	if (err)
+	err = wants_mount_setattr(uattr, usize, &kattr);
+	if (err <= 0)
 		return err;
 
 	err = user_path_at(dfd, path, kattr.lookup_flags, &target);
@@ -5282,15 +5288,17 @@ SYSCALL_DEFINE5(open_tree_attr, int, dfd, const char __user *, filename,
 		if (flags & AT_RECURSIVE)
 			kattr.kflags |= MOUNT_KATTR_RECURSE;
 
-		ret = copy_mount_setattr(uattr, usize, &kattr);
-		if (ret)
+		ret = wants_mount_setattr(uattr, usize, &kattr);
+		if (ret < 0)
 			return ret;
 
-		ret = do_mount_setattr(&file->f_path, &kattr);
-		if (ret)
-			return ret;
+		if (ret) {
+			ret = do_mount_setattr(&file->f_path, &kattr);
+			if (ret)
+				return ret;
 
-		finish_mount_kattr(&kattr);
+			finish_mount_kattr(&kattr);
+		}
 	}
 
 	fd = get_unused_fd_flags(flags & O_CLOEXEC);