2 files changed, 364 insertions, 1 deletions

diff --git a/scripts/atomic/gen-atomics.sh b/scripts/atomic/gen-atomics.sh
index 27400b0cd732..000dc6437893 100644
--- a/scripts/atomic/gen-atomics.sh
+++ b/scripts/atomic/gen-atomics.sh
@@ -13,7 +13,7 @@ gen-atomic-long.sh              asm-generic/atomic-long.h
 gen-atomic-fallback.sh          linux/atomic-fallback.h
 EOF
 while read script header; do
-        ${ATOMICDIR}/${script} ${ATOMICTBL} > ${LINUXDIR}/include/${header}
+        /bin/sh ${ATOMICDIR}/${script} ${ATOMICTBL} > ${LINUXDIR}/include/${header}
         HASH="$(sha1sum ${LINUXDIR}/include/${header})"
         HASH="${HASH%% *}"
         printf "// %s\n" "${HASH}" >> ${LINUXDIR}/include/${header}
diff --git a/scripts/coccinelle/api/stream_open.cocci b/scripts/coccinelle/api/stream_open.cocci
new file mode 100644
index 000000000000..350145da7669
--- /dev/null
+++ b/scripts/coccinelle/api/stream_open.cocci
@@ -0,0 +1,363 @@
+// SPDX-License-Identifier: GPL-2.0
+// Author: Kirill Smelkov (kirr@nexedi.com)
+//
+// Search for stream-like files that are using nonseekable_open and convert
+// them to stream_open. A stream-like file is a file that does not use ppos in
+// its read and write. Rationale for the conversion is to avoid deadlock in
+// between read and write.
+
+virtual report
+virtual patch
+virtual explain  // explain decisions in the patch (SPFLAGS="-D explain")
+
+// stream-like reader & writer - ones that do not depend on f_pos.
+@ stream_reader @
+identifier readstream, ppos;
+identifier f, buf, len;
+type loff_t;
+@@
+  ssize_t readstream(struct file *f, char *buf, size_t len, loff_t *ppos)
+  {
+    ... when != ppos
+  }
+
+@ stream_writer @
+identifier writestream, ppos;
+identifier f, buf, len;
+type loff_t;
+@@
+  ssize_t writestream(struct file *f, const char *buf, size_t len, loff_t *ppos)
+  {
+    ... when != ppos
+  }
+
+
+// a function that blocks
+@ blocks @
+identifier block_f;
+identifier wait_event =~ "^wait_event_.*";
+@@
+  block_f(...) {
+    ... when exists
+    wait_event(...)
+    ... when exists
+  }
+
+// stream_reader that can block inside.
+//
+// XXX wait_* can be called not directly from current function (e.g. func -> f -> g -> wait())
+// XXX currently reader_blocks supports only direct and 1-level indirect cases.
+@ reader_blocks_direct @
+identifier stream_reader.readstream;
+identifier wait_event =~ "^wait_event_.*";
+@@
+  readstream(...)
+  {
+    ... when exists
+    wait_event(...)
+    ... when exists
+  }
+
+@ reader_blocks_1 @
+identifier stream_reader.readstream;
+identifier blocks.block_f;
+@@
+  readstream(...)
+  {
+    ... when exists
+    block_f(...)
+    ... when exists
+  }
+
+@ reader_blocks depends on reader_blocks_direct || reader_blocks_1 @
+identifier stream_reader.readstream;
+@@
+  readstream(...) {
+    ...
+  }
+
+
+// file_operations + whether they have _any_ .read, .write, .llseek ... at all.
+//
+// XXX add support for file_operations xxx[N] = ...     (sound/core/pcm_native.c)
+@ fops0 @
+identifier fops;
+@@
+  struct file_operations fops = {
+    ...
+  };
+
+@ has_read @
+identifier fops0.fops;
+identifier read_f;
+@@
+  struct file_operations fops = {
+    .read = read_f,
+  };
+
+@ has_read_iter @
+identifier fops0.fops;
+identifier read_iter_f;
+@@
+  struct file_operations fops = {
+    .read_iter = read_iter_f,
+  };
+
+@ has_write @
+identifier fops0.fops;
+identifier write_f;
+@@
+  struct file_operations fops = {
+    .write = write_f,
+  };
+
+@ has_write_iter @
+identifier fops0.fops;
+identifier write_iter_f;
+@@
+  struct file_operations fops = {
+    .write_iter = write_iter_f,
+  };
+
+@ has_llseek @
+identifier fops0.fops;
+identifier llseek_f;
+@@
+  struct file_operations fops = {
+    .llseek = llseek_f,
+  };
+
+@ has_no_llseek @
+identifier fops0.fops;
+@@
+  struct file_operations fops = {
+    .llseek = no_llseek,
+  };
+
+@ has_mmap @
+identifier fops0.fops;
+identifier mmap_f;
+@@
+  struct file_operations fops = {
+    .mmap = mmap_f,
+  };
+
+@ has_copy_file_range @
+identifier fops0.fops;
+identifier copy_file_range_f;
+@@
+  struct file_operations fops = {
+    .copy_file_range = copy_file_range_f,
+  };
+
+@ has_remap_file_range @
+identifier fops0.fops;
+identifier remap_file_range_f;
+@@
+  struct file_operations fops = {
+    .remap_file_range = remap_file_range_f,
+  };
+
+@ has_splice_read @
+identifier fops0.fops;
+identifier splice_read_f;
+@@
+  struct file_operations fops = {
+    .splice_read = splice_read_f,
+  };
+
+@ has_splice_write @
+identifier fops0.fops;
+identifier splice_write_f;
+@@
+  struct file_operations fops = {
+    .splice_write = splice_write_f,
+  };
+
+
+// file_operations that is candidate for stream_open conversion - it does not
+// use mmap and other methods that assume @offset access to file.
+//
+// XXX for simplicity require no .{read/write}_iter and no .splice_{read/write} for now.
+// XXX maybe_steam.fops cannot be used in other rules - it gives "bad rule maybe_stream or bad variable fops".
+@ maybe_stream depends on (!has_llseek || has_no_llseek) && !has_mmap && !has_copy_file_range && !has_remap_file_range && !has_read_iter && !has_write_iter && !has_splice_read && !has_splice_write @
+identifier fops0.fops;
+@@
+  struct file_operations fops = {
+  };
+
+
+// ---- conversions ----
+
+// XXX .open = nonseekable_open -> .open = stream_open
+// XXX .open = func -> openfunc -> nonseekable_open
+
+// read & write
+//
+// if both are used in the same file_operations together with an opener -
+// under that conditions we can use stream_open instead of nonseekable_open.
+@ fops_rw depends on maybe_stream @
+identifier fops0.fops, openfunc;
+identifier stream_reader.readstream;
+identifier stream_writer.writestream;
+@@
+  struct file_operations fops = {
+      .open  = openfunc,
+      .read  = readstream,
+      .write = writestream,
+  };
+
+@ report_rw depends on report @
+identifier fops_rw.openfunc;
+position p1;
+@@
+  openfunc(...) {
+    <...
+     nonseekable_open@p1
+    ...>
+  }
+
+@ script:python depends on report && reader_blocks @
+fops << fops0.fops;
+p << report_rw.p1;
+@@
+coccilib.report.print_report(p[0],
+  "ERROR: %s: .read() can deadlock .write(); change nonseekable_open -> stream_open to fix." % (fops,))
+
+@ script:python depends on report && !reader_blocks @
+fops << fops0.fops;
+p << report_rw.p1;
+@@
+coccilib.report.print_report(p[0],
+  "WARNING: %s: .read() and .write() have stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))
+
+
+@ explain_rw_deadlocked depends on explain && reader_blocks @
+identifier fops_rw.openfunc;
+@@
+  openfunc(...) {
+    <...
+-    nonseekable_open
++    nonseekable_open /* read & write (was deadlock) */
+    ...>
+  }
+
+
+@ explain_rw_nodeadlock depends on explain && !reader_blocks @
+identifier fops_rw.openfunc;
+@@
+  openfunc(...) {
+    <...
+-    nonseekable_open
++    nonseekable_open /* read & write (no direct deadlock) */
+    ...>
+  }
+
+@ patch_rw depends on patch @
+identifier fops_rw.openfunc;
+@@
+  openfunc(...) {
+    <...
+-   nonseekable_open
++   stream_open
+    ...>
+  }
+
+
+// read, but not write
+@ fops_r depends on maybe_stream && !has_write @
+identifier fops0.fops, openfunc;
+identifier stream_reader.readstream;
+@@
+  struct file_operations fops = {
+      .open  = openfunc,
+      .read  = readstream,
+  };
+
+@ report_r depends on report @
+identifier fops_r.openfunc;
+position p1;
+@@
+  openfunc(...) {
+    <...
+    nonseekable_open@p1
+    ...>
+  }
+
+@ script:python depends on report @
+fops << fops0.fops;
+p << report_r.p1;
+@@
+coccilib.report.print_report(p[0],
+  "WARNING: %s: .read() has stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))
+
+@ explain_r depends on explain @
+identifier fops_r.openfunc;
+@@
+  openfunc(...) {
+    <...
+-   nonseekable_open
++   nonseekable_open /* read only */
+    ...>
+  }
+
+@ patch_r depends on patch @
+identifier fops_r.openfunc;
+@@
+  openfunc(...) {
+    <...
+-   nonseekable_open
++   stream_open
+    ...>
+  }
+
+
+// write, but not read
+@ fops_w depends on maybe_stream && !has_read @
+identifier fops0.fops, openfunc;
+identifier stream_writer.writestream;
+@@
+  struct file_operations fops = {
+      .open  = openfunc,
+      .write = writestream,
+  };
+
+@ report_w depends on report @
+identifier fops_w.openfunc;
+position p1;
+@@
+  openfunc(...) {
+    <...
+    nonseekable_open@p1
+    ...>
+  }
+
+@ script:python depends on report @
+fops << fops0.fops;
+p << report_w.p1;
+@@
+coccilib.report.print_report(p[0],
+  "WARNING: %s: .write() has stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))
+
+@ explain_w depends on explain @
+identifier fops_w.openfunc;
+@@
+  openfunc(...) {
+    <...
+-   nonseekable_open
++   nonseekable_open /* write only */
+    ...>
+  }
+
+@ patch_w depends on patch @
+identifier fops_w.openfunc;
+@@
+  openfunc(...) {
+    <...
+-   nonseekable_open
++   stream_open
+    ...>
+  }
+
+
+// no read, no write - don't change anything