<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/mmc/core/debugfs.c, branch v3.4.73</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>mmc: core: HS200 mode support for eMMC 4.5</title>
<updated>2012-01-12T20:17:15+00:00</updated>
<author>
<name>Girish K S</name>
<email>girish.shivananjappa@linaro.org</email>
</author>
<published>2012-01-11T19:04:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a4924c71aa43d4f8a3f342b1f71788349472e684'/>
<id>a4924c71aa43d4f8a3f342b1f71788349472e684</id>
<content type='text'>
This patch adds the support of the HS200 bus speed for eMMC 4.5 devices.
The eMMC 4.5 devices have support for 200MHz bus speed. The function
prototype of the tuning function is modified to handle the tuning
command number which is different in sd and mmc case.

Signed-off-by: Girish K S &lt;girish.shivananjappa@linaro.org&gt;
Signed-off-by: Philip Rakity &lt;prakity@marvell.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch adds the support of the HS200 bus speed for eMMC 4.5 devices.
The eMMC 4.5 devices have support for 200MHz bus speed. The function
prototype of the tuning function is modified to handle the tuning
command number which is different in sd and mmc case.

Signed-off-by: Girish K S &lt;girish.shivananjappa@linaro.org&gt;
Signed-off-by: Philip Rakity &lt;prakity@marvell.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: debugfs: expose the SDCLK frq in sys ios</title>
<updated>2012-01-12T04:58:40+00:00</updated>
<author>
<name>Giuseppe CAVALLARO</name>
<email>peppe.cavallaro@st.com</email>
</author>
<published>2011-11-04T12:53:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=df16219f365f7f5a2d88a6e123251d57255cca3f'/>
<id>df16219f365f7f5a2d88a6e123251d57255cca3f</id>
<content type='text'>
This patch is to expose the actual SDCLK frequency in
/sys/kernel/debug/mmcX/ios entry.

For example, if the max clk for a normal speed card is 20MHz this
is reported in /sys/kernel/debug/mmcX/ios.  Unfortunately the actual
SDCLK frequency (i.e. Baseclock / divisor) is not reported at all:
for example, in that case, on Arasan HC, it should be 48/4=12 (MHz).

Signed-off-by: Giuseppe Cavallaro &lt;peppe.cavallaro@st.com&gt;
Acked-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch is to expose the actual SDCLK frequency in
/sys/kernel/debug/mmcX/ios entry.

For example, if the max clk for a normal speed card is 20MHz this
is reported in /sys/kernel/debug/mmcX/ios.  Unfortunately the actual
SDCLK frequency (i.e. Baseclock / divisor) is not reported at all:
for example, in that case, on Arasan HC, it should be 48/4=12 (MHz).

Signed-off-by: Giuseppe Cavallaro &lt;peppe.cavallaro@st.com&gt;
Acked-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: Add export.h for EXPORT_SYMBOL/THIS_MODULE as required</title>
<updated>2011-10-31T23:32:06+00:00</updated>
<author>
<name>Paul Gortmaker</name>
<email>paul.gortmaker@windriver.com</email>
</author>
<published>2011-07-10T16:42:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3ef77af154b03776c6c662c68c6332719e9eecac'/>
<id>3ef77af154b03776c6c662c68c6332719e9eecac</id>
<content type='text'>
These two basic defines were everywhere, simply because module.h
was also everywhere.   But we are cleaning up the latter.  So make
the exporters actually call out their need for the include.

Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
These two basic defines were everywhere, simply because module.h
was also everywhere.   But we are cleaning up the latter.  So make
the exporters actually call out their need for the include.

Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: using module_param requires the inclusion of moduleparam.h</title>
<updated>2011-10-26T20:32:18+00:00</updated>
<author>
<name>Stephen Rothwell</name>
<email>sfr@canb.auug.org.au</email>
</author>
<published>2011-10-09T14:35:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3f102ae926c01bccc9520a62cff833fde889ed6a'/>
<id>3f102ae926c01bccc9520a62cff833fde889ed6a</id>
<content type='text'>
Commit "mmc: add module param to set fault injection attributes" adds
a module_param to this file.  But it is relying on the old implicit
"module.h is everywhere" behaviour, and without the explicit include
of moduleparam.h, the pending module.h split up produces this error:

core/debugfs.c:28:35: error: expected ')' before numeric constant

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit "mmc: add module param to set fault injection attributes" adds
a module_param to this file.  But it is relying on the old implicit
"module.h is everywhere" behaviour, and without the explicit include
of moduleparam.h, the pending module.h split up produces this error:

core/debugfs.c:28:35: error: expected ')' before numeric constant

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: add module param to set fault injection attributes</title>
<updated>2011-10-26T20:32:12+00:00</updated>
<author>
<name>Per Forlin</name>
<email>per.forlin@linaro.org</email>
</author>
<published>2011-09-13T21:03:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=34f5050800d600551cca9bcfb463cc6699d82d04'/>
<id>34f5050800d600551cca9bcfb463cc6699d82d04</id>
<content type='text'>
Replace setup("fail_mmc_request") and faulty "ifdef KERNEL" with
a simple module_param(). The module param mmc_core.fail_request
may be used to set the fault injection attributes during boot time
or module load time.

Signed-off-by: Per Forlin &lt;per.forlin@linaro.org&gt;
Reviewed-by: Akinobu Mita &lt;akinobu.mita@gmail.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replace setup("fail_mmc_request") and faulty "ifdef KERNEL" with
a simple module_param(). The module param mmc_core.fail_request
may be used to set the fault injection attributes during boot time
or module load time.

Signed-off-by: Per Forlin &lt;per.forlin@linaro.org&gt;
Reviewed-by: Akinobu Mita &lt;akinobu.mita@gmail.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: core: add sd uhs string for mmc_ios_show</title>
<updated>2011-10-26T20:32:10+00:00</updated>
<author>
<name>Aaron Lu</name>
<email>aaron.lu@amd.com</email>
</author>
<published>2011-09-02T08:06:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=cd8a3666987ba20908bbeb7c78ed9ba82b365643'/>
<id>cd8a3666987ba20908bbeb7c78ed9ba82b365643</id>
<content type='text'>
This is a minor fix. It makes mmc_ios_show print proper string when the
host's timing is one of the newly added UHS-I modes.

Signed-off-by: Aaron Lu &lt;aaron.lu@amd.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is a minor fix. It makes mmc_ios_show print proper string when the
host's timing is one of the newly added UHS-I modes.

Signed-off-by: Aaron Lu &lt;aaron.lu@amd.com&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: core: add random fault injection</title>
<updated>2011-10-26T19:43:34+00:00</updated>
<author>
<name>Per Forlin</name>
<email>per.forlin@linaro.org</email>
</author>
<published>2011-08-19T12:52:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=1b676f70c108cda90cf9d114d16c677584400efc'/>
<id>1b676f70c108cda90cf9d114d16c677584400efc</id>
<content type='text'>
This adds support to inject data errors after a completed host transfer.
The mmc core will return error even though the host transfer is successful.
This simple fault injection proved to be very useful to test the
non-blocking error handling in the mmc_blk_issue_rw_rq().
Random faults can also test how the host driver handles pre_req()
and post_req() in case of errors.

Signed-off-by: Per Forlin &lt;per.forlin@linaro.org&gt;
Acked-by: Akinobu Mita &lt;akinobu.mita@gmail.com&gt;
Reviewed-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This adds support to inject data errors after a completed host transfer.
The mmc core will return error even though the host transfer is successful.
This simple fault injection proved to be very useful to test the
non-blocking error handling in the mmc_blk_issue_rw_rq().
Random faults can also test how the host driver handles pre_req()
and post_req() in case of errors.

Signed-off-by: Per Forlin &lt;per.forlin@linaro.org&gt;
Acked-by: Akinobu Mita &lt;akinobu.mita@gmail.com&gt;
Reviewed-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: Aggressive clock gating framework</title>
<updated>2011-01-09T03:48:03+00:00</updated>
<author>
<name>Linus Walleij</name>
<email>linus.walleij@stericsson.com</email>
</author>
<published>2010-11-09T02:36:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=04566831a703ae3ef4b49a2deae261c9ed26e020'/>
<id>04566831a703ae3ef4b49a2deae261c9ed26e020</id>
<content type='text'>
This patch modifies the MMC core code to optionally call the set_ios()
operation on the driver with the clock frequency set to 0 (gate) after
a grace period of at least 8 MCLK cycles, then restore it (ungate)
before any new request. This gives the driver the option to shut down
the MCI clock to the MMC/SD card when the clock frequency is 0, i.e.
the core has stated that the MCI clock does not need to be generated.

It is inspired by existing clock gating code found in the OMAP and
Atmel drivers and brings this up to the host abstraction.  Gating is
performed before and after any MMC request.

This patchset implements this for the MMCI/PL180 MMC/SD host controller,
but it should be simple to switch OMAP/Atmel over to using this instead.

mmc_set_{gated,ungated}() add variable protection to the state holders
for the clock gating code.  This is particularly important when ordinary
.set_ios() calls would race with the .set_ios() call resulting from a
delayed gate operation.

Signed-off-by: Linus Walleij &lt;linus.walleij@stericsson.com&gt;
Reviewed-by: Chris Ball &lt;cjb@laptop.org&gt;
Tested-by: Chris Ball &lt;cjb@laptop.org&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch modifies the MMC core code to optionally call the set_ios()
operation on the driver with the clock frequency set to 0 (gate) after
a grace period of at least 8 MCLK cycles, then restore it (ungate)
before any new request. This gives the driver the option to shut down
the MCI clock to the MMC/SD card when the clock frequency is 0, i.e.
the core has stated that the MCI clock does not need to be generated.

It is inspired by existing clock gating code found in the OMAP and
Atmel drivers and brings this up to the host abstraction.  Gating is
performed before and after any MMC request.

This patchset implements this for the MMCI/PL180 MMC/SD host controller,
but it should be simple to switch OMAP/Atmel over to using this instead.

mmc_set_{gated,ungated}() add variable protection to the state holders
for the clock gating code.  This is particularly important when ordinary
.set_ios() calls would race with the .set_ios() call resulting from a
delayed gate operation.

Signed-off-by: Linus Walleij &lt;linus.walleij@stericsson.com&gt;
Reviewed-by: Chris Ball &lt;cjb@laptop.org&gt;
Tested-by: Chris Ball &lt;cjb@laptop.org&gt;
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mmc: add a file to debugfs for changing host clock at runtime</title>
<updated>2010-10-23T13:11:20+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andy.shevchenko@gmail.com</email>
</author>
<published>2010-10-13T08:22:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=703aae3d09a4b351866f1a97b2afafb905bdbf1e'/>
<id>703aae3d09a4b351866f1a97b2afafb905bdbf1e</id>
<content type='text'>
For debugging power management features it is convenient to have the
possibility of changing the MMC host controller clock at runtime.  This
patch adds a 'clock' file for this under the MMC host root of debugfs.

Usage is as follows:

	# cat /sys/kernel/debug/mmc0/clock
	52000000

	# echo "1000000000" &gt; /sys/kernel/debug/mmc0/clock
	# cat /sys/kernel/debug/mmc0/clock
	52000000

	# echo "48000000" &gt; /sys/kernel/debug/mmc0/clock
	# cat /sys/kernel/debug/mmc0/clock
	48000000

The middle example shows limits being applied by the host driver.

Signed-off-by: Andy Shevchenko &lt;ext-andriy.shevchenko@nokia.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@nokia.com&gt;
[cjb: modify changelog language]
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
For debugging power management features it is convenient to have the
possibility of changing the MMC host controller clock at runtime.  This
patch adds a 'clock' file for this under the MMC host root of debugfs.

Usage is as follows:

	# cat /sys/kernel/debug/mmc0/clock
	52000000

	# echo "1000000000" &gt; /sys/kernel/debug/mmc0/clock
	# cat /sys/kernel/debug/mmc0/clock
	52000000

	# echo "48000000" &gt; /sys/kernel/debug/mmc0/clock
	# cat /sys/kernel/debug/mmc0/clock
	48000000

The middle example shows limits being applied by the host driver.

Signed-off-by: Andy Shevchenko &lt;ext-andriy.shevchenko@nokia.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@nokia.com&gt;
[cjb: modify changelog language]
Signed-off-by: Chris Ball &lt;cjb@laptop.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>llseek: automatically add .llseek fop</title>
<updated>2010-10-15T13:53:27+00:00</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2010-08-15T16:52:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6038f373a3dc1f1c26496e60b6c40b164716f07e'/>
<id>6038f373a3dc1f1c26496e60b6c40b164716f07e</id>
<content type='text'>
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(...)
{
&lt;+...
nonseekable_open(...)
...+&gt;
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
&lt;+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+&gt;
}

@ 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)
{
&lt;+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+&gt;
}

@ 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)
{
&lt;+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+&gt;
}

@ 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 &amp;&amp; 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 &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !fops2 &amp;&amp; !fops3 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_read &amp;&amp; !fops1 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_write &amp;&amp; !fops1 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_write &amp;&amp; !fops1 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Julia Lawall &lt;julia@diku.dk&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
</content>
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<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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(...)
{
&lt;+...
nonseekable_open(...)
...+&gt;
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
&lt;+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+&gt;
}

@ 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)
{
&lt;+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+&gt;
}

@ 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)
{
&lt;+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+&gt;
}

@ 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 &amp;&amp; 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 &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !fops2 &amp;&amp; !fops3 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_read &amp;&amp; !fops1 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_write &amp;&amp; !fops1 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !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 &amp;&amp; !has_write &amp;&amp; !fops1 &amp;&amp; !fops2 &amp;&amp; !has_llseek &amp;&amp; !nonseekable1 &amp;&amp; !nonseekable2 &amp;&amp; !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Julia Lawall &lt;julia@diku.dk&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
</pre>
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</entry>
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