From 3975b097e577bac77267ed8df0f525e3ad3499ec Mon Sep 17 00:00:00 2001
From: Kirill Smelkov <kirr@nexedi.com>
Date: Wed, 19 Jun 2019 20:26:56 +0300
Subject: [PATCH] *: convert stream-like files -> stream_open, even if they use
noop_llseek
This patch continues 10dce8af3422 (fs: stream_open - opener for
stream-like files so that read and write can run simultaneously without
deadlock) and c5bf68fe0c86 (*: convert stream-like files from
nonseekable_open -> stream_open) and teaches steam_open.cocci to
consider files as being stream-like not only if they have
.llseek=no_llseek, but also if they have .llseek=noop_llseek.
This is safe to do: the comment about noop_llseek says
This is an implementation of ->llseek useable for the rare special case when
userspace expects the seek to succeed but the (device) file is actually not
able to perform the seek. In this case you use noop_llseek() instead of
falling back to the default implementation of ->llseek.
and in general noop_llseek was massively added to drivers in 6038f373a3dc
(llseek: automatically add .llseek fop) when changing default for NULL .llseek
from NOP to no_llseek with the idea to avoid breaking compatibility, if
maybe some user-space program was using lseek on a device without caring
about the result, but caring if it was an error or not.
Amended semantic patch produces two changes when applied tree-wide:
drivers/hid/hid-sensor-custom.c:690:8-24: WARNING: hid_sensor_custom_fops: .read() has stream semantic; safe to change nonseekable_open -> stream_open.
drivers/input/mousedev.c:564:1-17: ERROR: mousedev_fops: .read() can deadlock .write(); change nonseekable_open -> stream_open to fix.
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Jan Blunck <jblunck@suse.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
---
drivers/hid/hid-sensor-custom.c | 2 +-
drivers/input/mousedev.c | 2 +-
scripts/coccinelle/api/stream_open.cocci | 9 ++++++++-
3 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/hid/hid-sensor-custom.c b/drivers/hid/hid-sensor-custom.c
index c60f82673cf28..fb827c295842f 100644
--- a/drivers/hid/hid-sensor-custom.c
+++ b/drivers/hid/hid-sensor-custom.c
@@ -687,7 +687,7 @@ static int hid_sensor_custom_open(struct inode *inode, struct file *file)
if (test_and_set_bit(0, &sensor_inst->misc_opened))
return -EBUSY;
- return nonseekable_open(inode, file);
+ return stream_open(inode, file);
}
static __poll_t hid_sensor_custom_poll(struct file *file,
diff --git a/drivers/input/mousedev.c b/drivers/input/mousedev.c
index 3b73e0f17848c..505c562a5daa1 100644
--- a/drivers/input/mousedev.c
+++ b/drivers/input/mousedev.c
@@ -558,7 +558,7 @@ static int mousedev_open(struct inode *inode, struct file *file)
goto err_free_client;
file->private_data = client;
- nonseekable_open(inode, file);
+ stream_open(inode, file);
return 0;
diff --git a/scripts/coccinelle/api/stream_open.cocci b/scripts/coccinelle/api/stream_open.cocci
index 350145da76691..f00c05d207d9c 100644
--- a/scripts/coccinelle/api/stream_open.cocci
+++ b/scripts/coccinelle/api/stream_open.cocci
@@ -134,6 +134,13 @@ identifier fops0.fops;
.llseek = no_llseek,
};
+@ has_noop_llseek @
+identifier fops0.fops;
+@@
+ struct file_operations fops = {
+ .llseek = noop_llseek,
+ };
+
@ has_mmap @
identifier fops0.fops;
identifier mmap_f;
@@ -180,7 +187,7 @@ identifier splice_write_f;
//
// 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 @
+@ maybe_stream depends on (!has_llseek || has_no_llseek || has_noop_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 = {
--
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