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All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.
The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.
New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time. Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.
The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.
Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.
Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.
===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
// but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}
@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}
@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}
@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}
@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}
@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}
@ fops0 @
identifier fops;
@@
struct file_operations fops = {
...
};
@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
.llseek = llseek_f,
...
};
@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
.read = read_f,
...
};
@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
.write = write_f,
...
};
@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
.open = open_f,
...
};
// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
... .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};
@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
... .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};
// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
... .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};
// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};
// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};
@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+ .llseek = default_llseek, /* write accesses f_pos */
};
// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////
@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
.write = write_f,
.read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};
@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};
@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};
@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
|
|
Combination of the following changes:
Mon, 23 Feb 2009 14:21:10 +0100 (CET)
firedtv: reinstate debug logging option
Henrik Kurelid tells me that FCP debug logging (which I removed during
cleanups) is still useful when working on driver issues together with
end users. So bring it back in an updated form with only 60% of the
original code footprint.
Logging can be enabled with
# echo -1 > /sys/module/firedtv/parameters/debug
1 instead of -1 enables only FCP header logging,
2 instead of -1 enables only hexdumps of the entire FCP frames.
0 switches logging off again.
Fri, 20 Feb 2009 20:54:27 +0100 (CET)
firedtv: build fix for INPUT=m and DVB_FIREDTV=y
Thu, 19 Feb 2009 20:40:39 +0100
firedtv: use msecs_to_jiffies
Pointed out by Mauro Carvalho Chehab.
Sun Feb 15 20:50:46 CET 2009
firedtv: some more housekeeping
Fix an old checkpatch warning and a new compiler warning.
Sun Feb 15 15:33:17 CET 2009
firedtv: rename a file once more
At the moment, about a third of avc.c is specific to FireDTVs rather
than generic AV/C code. Rename it to firedtv-avc.c.
Sun Feb 15 15:33:17 CET 2009
firedtv: dvb demux: more compact channels backing store
Replace struct firedtv_channel { bool active; int pid; } channel[16];
by unsigned long channel_active; u16 channel_pid[16];.
Sun Feb 15 15:33:17 CET 2009
firedtv: dvb demux: some simplifications
c->active was unnecessarily cleared twice.
Also, by marking the channel inactive before the for loop,
the loop becomes identical with fdtv_channel_collect().
Sun Feb 15 15:33:17 CET 2009
firedtv: dvb demux: remove a bogus loop
This loop is unnecessary because
- only active channel[].pid's will be sent to the device,
- when a channel is activated, its pid is set to dvbdmxfeed->pid.
Perhaps the original code was there because it was initially not fully
covered by the fdtv->demux_mutex.
Sun Feb 15 15:33:17 CET 2009
firedtv: dvb demux: fix mutex protection
fdtv_start_feed() accessed the channel list unsafely.
Fully serialize it with itself and fdtv_stop_feed().
Sun Feb 15 15:33:17 CET 2009
firedtv: dvb demux: fix missing braces
Original code was:
...
case DMX_TS_PES_OTHER:
//Dirty fix to keep firesat->channel pid-list up to date
for(k=0;k<16;k++){
if(firesat->channel[k].active == 0)
firesat->channel[k].pid =
dvbdmxfeed->pid;
break;
}
channel = firesat_channel_allocate(firesat);
break;
default:
...
Looks bogus in several respects. For now let's just add braces to the if
because that seems to be what the author meant.
Sun Feb 15 15:33:17 CET 2009
firedtv: allow build without input subsystem
!CONFIG_INPUT is very unlikely on systems on which firedtv is of
interest. But we can easily support it.
Sun Feb 15 15:33:17 CET 2009
firedtv: replace EXTRA_CFLAGS by ccflags
The former are deprecated.
The latter can depend on Kconfig variables.
Sun Feb 15 15:33:17 CET 2009
firedtv: concentrate ieee1394 dependencies
Move the entire interface with drivers/ieee1394 to firedtv-1394.c.
Move 1394-independent module initialization code to firedtv-dvb.c.
This prepares interfacing with drivers/firewire.
Sun Feb 15 15:33:17 CET 2009
firedtv: amend Kconfig menu prompt
Sun Feb 15 15:33:17 CET 2009
firedtv: remove kernel version compatibility macro
Sun Feb 15 15:33:17 CET 2009
firedtv: combine header files
avc.h and firedtv-*.h are small and currently not shared with other
drivers, hence concatenate them all into firedtv.h.
Sun Feb 15 15:33:17 CET 2009
firedtv: misc style touch-ups
Standardize on lower-case hexadecimal constants. Adjust whitespace.
Omit unnecessary pointer type casts and an unnecessary list head
initialization. Use dev_printk.
Wed Feb 11 21:21:04 CET 2009
firedtv: avc, ci: remove unused constants
Wed Feb 11 21:21:04 CET 2009
firedtv: avc: remove bitfields from read descriptor response operands
Don't use bitfields in struct types of on-the-wire data.
Wed Feb 11 21:21:04 CET 2009
firedtv: avc: remove bitfields from DSD command operands
Don't use bitfields in struct types of on-the-wire data.
Wed Feb 11 21:21:04 CET 2009
firedtv: avc: header file cleanup
Remove unused constants and declarations.
Move privately used constants into .c files.
Wed Feb 11 21:21:04 CET 2009
firedtv: avc: remove bitfields from FCP frame types
Don't use bitfields in struct types of on-the-wire data.
Also move many privately used constants from avc.h to avc.c
and remove some unused constants.
Sun, 18 Jan 2009 16:30:00 +0100 (CET)
firedtv: avc: fix offset in avc_tuner_get_ts
The parentheses were wrong. It didn't matter though because this code
only writes a 0 into an area which is already initialized to 0.
Sun, 18 Jan 2009 16:30:00 +0100 (CET)
firedtv: avc: reduce stack usage, remove two typedefs
It is safe to share a memory buffer for command frame and response frame
because the response data come in after the command frame was last used.
Even less stack would be required if only the actual required frame size
instead of the entire FCP register size was allocated.
Also, rename the defined types AVCCmdFrm and AVCRspFrm to
struct avc_command_frame and struct avc_response_frame.
TODO: Remove the bitfields in these types.
Sun, 18 Jan 2009 16:30:00 +0100 (CET)
firedtv: cmp: move code to avc
Sun, 18 Jan 2009 16:30:00 +0100 (CET)
firedtv: iso: move code to firedtv-1394
Sun, 18 Jan 2009 16:30:00 +0100 (CET)
firedtv: iso: remove unnecessary struct type definitions
Sun, 18 Jan 2009 16:30:00 +0100 (CET)
firedtv: iso: style changes and fixlets
Add cleanup after failure in setup_iso_channel.
Replace printk() by dv_err().
Decrease indentation level in rawiso_activity_cb().
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
|
Mauro Carvalho Chehab
Stefan Richter
Arnd Bergmann
Alexey Dobriyan
Rambaldi