Merge tag 'socfpga_fix_for_v5.16_part_3' of git://git.kernel.org/pub/scm/linux/kernel/git/dinguyen/linux into arm/fixes

SoCFPGA dts updates for v5.16, part 3
- Change the SoCFPGA compatible to "intel,socfpga-qspi"
- Update dt-bindings document to include "intel,socfpga-qspi"

* tag 'socfpga_fix_for_v5.16_part_3' of git://git.kernel.org/pub/scm/linux/kernel/git/dinguyen/linux: (361 commits)
  ARM: dts: socfpga: change qspi to "intel,socfpga-qspi"
  dt-bindings: spi: cadence-quadspi: document "intel,socfpga-qspi"
  Linux 5.16-rc7
  mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page()
  mm/damon/dbgfs: protect targets destructions with kdamond_lock
  mm/page_alloc: fix __alloc_size attribute for alloc_pages_exact_nid
  mm: delete unsafe BUG from page_cache_add_speculative()
  mm, hwpoison: fix condition in free hugetlb page path
  MAINTAINERS: mark more list instances as moderated
  kernel/crash_core: suppress unknown crashkernel parameter warning
  mm: mempolicy: fix THP allocations escaping mempolicy restrictions
  kfence: fix memory leak when cat kfence objects
  platform/x86: intel_pmc_core: fix memleak on registration failure
  net: stmmac: dwmac-visconti: Fix value of ETHER_CLK_SEL_FREQ_SEL_2P5M
  r8152: sync ocp base
  r8152: fix the force speed doesn't work for RTL8156
  net: bridge: fix ioctl old_deviceless bridge argument
  net: stmmac: ptp: fix potentially overflowing expression
  net: dsa: tag_ocelot: use traffic class to map priority on injected header
  veth: ensure skb entering GRO are not cloned.
  ...

Link: https://lore.kernel.org/r/20211227103644.566694-1-dinguyen@kernel.org
Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 56 insertions, 16 deletions

diff --git a/fs/file.c b/fs/file.c
index ad4a8bf3cf10..97d212a9b814 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -841,28 +841,68 @@ void do_close_on_exec(struct files_struct *files)
 	spin_unlock(&files->file_lock);
 }
 
-static struct file *__fget_files(struct files_struct *files, unsigned int fd,
-				 fmode_t mask, unsigned int refs)
+static inline struct file *__fget_files_rcu(struct files_struct *files,
+	unsigned int fd, fmode_t mask, unsigned int refs)
 {
-	struct file *file;
+	for (;;) {
+		struct file *file;
+		struct fdtable *fdt = rcu_dereference_raw(files->fdt);
+		struct file __rcu **fdentry;
 
-	rcu_read_lock();
-loop:
-	file = files_lookup_fd_rcu(files, fd);
-	if (file) {
-		/* File object ref couldn't be taken.
-		 * dup2() atomicity guarantee is the reason
-		 * we loop to catch the new file (or NULL pointer)
+		if (unlikely(fd >= fdt->max_fds))
+			return NULL;
+
+		fdentry = fdt->fd + array_index_nospec(fd, fdt->max_fds);
+		file = rcu_dereference_raw(*fdentry);
+		if (unlikely(!file))
+			return NULL;
+
+		if (unlikely(file->f_mode & mask))
+			return NULL;
+
+		/*
+		 * Ok, we have a file pointer. However, because we do
+		 * this all locklessly under RCU, we may be racing with
+		 * that file being closed.
+		 *
+		 * Such a race can take two forms:
+		 *
+		 *  (a) the file ref already went down to zero,
+		 *      and get_file_rcu_many() fails. Just try
+		 *      again:
 		 */
-		if (file->f_mode & mask)
-			file = NULL;
-		else if (!get_file_rcu_many(file, refs))
-			goto loop;
-		else if (files_lookup_fd_raw(files, fd) != file) {
+		if (unlikely(!get_file_rcu_many(file, refs)))
+			continue;
+
+		/*
+		 *  (b) the file table entry has changed under us.
+		 *       Note that we don't need to re-check the 'fdt->fd'
+		 *       pointer having changed, because it always goes
+		 *       hand-in-hand with 'fdt'.
+		 *
+		 * If so, we need to put our refs and try again.
+		 */
+		if (unlikely(rcu_dereference_raw(files->fdt) != fdt) ||
+		    unlikely(rcu_dereference_raw(*fdentry) != file)) {
 			fput_many(file, refs);
-			goto loop;
+			continue;
 		}
+
+		/*
+		 * Ok, we have a ref to the file, and checked that it
+		 * still exists.
+		 */
+		return file;
 	}
+}
+
+static struct file *__fget_files(struct files_struct *files, unsigned int fd,
+				 fmode_t mask, unsigned int refs)
+{
+	struct file *file;
+
+	rcu_read_lock();
+	file = __fget_files_rcu(files, fd, mask, refs);
 	rcu_read_unlock();
 
 	return file;