<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux/drivers/char/random.c, branch v3.0</title>
<subtitle>Mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
</subtitle>
<id>https://git.shady.money/linux/atom?h=v3.0</id>
<link rel='self' href='https://git.shady.money/linux/atom?h=v3.0'/>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/'/>
<updated>2011-03-31T14:26:23Z</updated>
<entry>
<title>Fix common misspellings</title>
<updated>2011-03-31T14:26:23Z</updated>
<author>
<name>Lucas De Marchi</name>
<email>lucas.demarchi@profusion.mobi</email>
</author>
<published>2011-03-31T01:57:33Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=25985edcedea6396277003854657b5f3cb31a628'/>
<id>urn:sha1:25985edcedea6396277003854657b5f3cb31a628</id>
<content type='text'>
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi &lt;lucas.demarchi@profusion.mobi&gt;
</content>
</entry>
<entry>
<title>random: update interface comments to reflect reality</title>
<updated>2011-02-21T11:42:42Z</updated>
<author>
<name>Jarod Wilson</name>
<email>jarod@redhat.com</email>
</author>
<published>2011-02-21T10:43:10Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=442a4fffffa26fc3080350b4d50172f7589c3ac2'/>
<id>urn:sha1:442a4fffffa26fc3080350b4d50172f7589c3ac2</id>
<content type='text'>
At present, the comment header in random.c makes no mention of
add_disk_randomness, and instead, suggests that disk activity adds to the
random pool by way of add_interrupt_randomness, which appears to not have
been the case since sometime prior to the existence of git, and even prior
to bitkeeper. Didn't look any further back. At least, as far as I can
tell, there are no storage drivers setting IRQF_SAMPLE_RANDOM, which is a
requirement for add_interrupt_randomness to trigger, so the only way for a
disk to contribute entropy is by way of add_disk_randomness. Update
comments accordingly, complete with special mention about solid state
drives being a crappy source of entropy (see e2e1a148bc for reference).

Signed-off-by: Jarod Wilson &lt;jarod@redhat.com&gt;
Acked-by: Matt Mackall &lt;mpm@selenic.com&gt;
Signed-off-by: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
</content>
</entry>
<entry>
<title>random: Use this_cpu_inc_return</title>
<updated>2010-12-17T14:18:05Z</updated>
<author>
<name>Christoph Lameter</name>
<email>cl@linux.com</email>
</author>
<published>2010-12-06T17:40:06Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=b29c617af3b09d150d3889836c24d39564b39180'/>
<id>urn:sha1:b29c617af3b09d150d3889836c24d39564b39180</id>
<content type='text'>
__this_cpu_inc can create a single instruction to do the same as
__get_cpu_var()++.

Cc: Richard Kennedy &lt;richard@rsk.demon.co.uk&gt;
Cc: Matt Mackall &lt;mpm@selenic.com&gt;
Acked-by: H. Peter Anvin &lt;hpa@zytor.com&gt;
Signed-off-by: Christoph Lameter &lt;cl@linux.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</content>
</entry>
<entry>
<title>llseek: automatically add .llseek fop</title>
<updated>2010-10-15T13:53:27Z</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2010-08-15T16:52:59Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=6038f373a3dc1f1c26496e60b6c40b164716f07e'/>
<id>urn:sha1:6038f373a3dc1f1c26496e60b6c40b164716f07e</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>
</entry>
<entry>
<title>random: Reorder struct entropy_store to remove padding on 64bits              </title>
<updated>2010-07-31T11:58:00Z</updated>
<author>
<name>Richard Kennedy</name>
<email>richard@rsk.demon.co.uk</email>
</author>
<published>2010-07-31T11:58:00Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=4015d9a865e3bcc42d88bedc8ce1551000bab664'/>
<id>urn:sha1:4015d9a865e3bcc42d88bedc8ce1551000bab664</id>
<content type='text'>
Re-order structure entropy_store to remove 8 bytes of padding on
64 bit builds, so shrinking this structure from 72 to 64 bytes
and allowing it to fit into one cache line.

Signed-off-by: Richard Kennedy &lt;richard@rsk.demon.co.uk&gt;
Signed-off-by: Matt Mackall &lt;mpm@selenic.com&gt;
Signed-off-by: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
</content>
</entry>
<entry>
<title>random: simplify fips mode</title>
<updated>2010-05-20T09:55:01Z</updated>
<author>
<name>Matt Mackall</name>
<email>mpm@selenic.com</email>
</author>
<published>2010-05-20T09:55:01Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=e954bc91bdd4bb08b8325478c5004b24a23a3522'/>
<id>urn:sha1:e954bc91bdd4bb08b8325478c5004b24a23a3522</id>
<content type='text'>
Rather than dynamically allocate 10 bytes, move it to static allocation.
This saves space and avoids the need for error checking.

Signed-off-by: Matt Mackall &lt;mpm@selenic.com&gt;
Signed-off-by: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
</content>
</entry>
<entry>
<title>Fix misspellings of "truly" in comments.</title>
<updated>2010-02-04T10:55:45Z</updated>
<author>
<name>Adam Buchbinder</name>
<email>adam.buchbinder@gmail.com</email>
</author>
<published>2009-12-11T21:35:39Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=c41b20e721ea4f6f20f66a66e7f0c3c97a2ca9c2'/>
<id>urn:sha1:c41b20e721ea4f6f20f66a66e7f0c3c97a2ca9c2</id>
<content type='text'>
Some comments misspell "truly"; this fixes them. No code changes.

Signed-off-by: Adam Buchbinder &lt;adam.buchbinder@gmail.com&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
</content>
</entry>
<entry>
<title>random: Remove unused inode variable</title>
<updated>2010-02-01T19:50:27Z</updated>
<author>
<name>Herbert Xu</name>
<email>herbert@gondor.apana.org.au</email>
</author>
<published>2010-02-01T10:48:28Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=cd1510cb5f892907fe1a662f90b41fb3a42954e0'/>
<id>urn:sha1:cd1510cb5f892907fe1a662f90b41fb3a42954e0</id>
<content type='text'>
The previous changeset left behind an unused inode variable.
This patch removes it.

Reported-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
</content>
</entry>
<entry>
<title>random: drop weird m_time/a_time manipulation</title>
<updated>2010-02-01T19:50:23Z</updated>
<author>
<name>Matt Mackall</name>
<email>mpm@selenic.com</email>
</author>
<published>2010-01-29T08:50:36Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=a996996dd75a9086b12d1cb4010f26e1748993f0'/>
<id>urn:sha1:a996996dd75a9086b12d1cb4010f26e1748993f0</id>
<content type='text'>
No other driver does anything remotely like this that I know of except
for the tty drivers, and I can't see any reason for random/urandom to do
it. In fact, it's a (trivial, harmless) timing information leak. And
obviously, it generates power- and flash-cycle wasting I/O, especially
if combined with something like hwrngd. Also, it breaks ubifs's
expectations.

Signed-off-by: Matt Mackall &lt;mpm@selenic.com&gt;
Signed-off-by: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
</content>
</entry>
<entry>
<title>random.c: use %pU to print UUIDs</title>
<updated>2009-12-15T16:53:33Z</updated>
<author>
<name>Joe Perches</name>
<email>joe@perches.com</email>
</author>
<published>2009-12-15T02:01:11Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=35900771c06cee858b725ef7069fb6934691b319'/>
<id>urn:sha1:35900771c06cee858b725ef7069fb6934691b319</id>
<content type='text'>
Signed-off-by: Joe Perches &lt;joe@perches.com&gt;
Acked-by: Matt Mackall &lt;mpm@selenic.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
</feed>
