Revision 474095e46cd14421821da3201a9fd6a4c070996b authored by Linus Torvalds on 24 April 2015, 16:28:01 UTC, committed by Linus Torvalds on 24 April 2015, 16:28:01 UTC
Pull md updates from Neil Brown: "More updates that usual this time. A few have performance impacts which hould mostly be positive, but RAID5 (in particular) can be very work-load ensitive... We'll have to wait and see. Highlights: - "experimental" code for managing md/raid1 across a cluster using DLM. Code is not ready for general use and triggers a WARNING if used. However it is looking good and mostly done and having in mainline will help co-ordinate development. - RAID5/6 can now batch multiple (4K wide) stripe_heads so as to handle a full (chunk wide) stripe as a single unit. - RAID6 can now perform read-modify-write cycles which should help performance on larger arrays: 6 or more devices. - RAID5/6 stripe cache now grows and shrinks dynamically. The value set is used as a minimum. - Resync is now allowed to go a little faster than the 'mininum' when there is competing IO. How much faster depends on the speed of the devices, so the effective minimum should scale with device speed to some extent" * tag 'md/4.1' of git://neil.brown.name/md: (58 commits) md/raid5: don't do chunk aligned read on degraded array. md/raid5: allow the stripe_cache to grow and shrink. md/raid5: change ->inactive_blocked to a bit-flag. md/raid5: move max_nr_stripes management into grow_one_stripe and drop_one_stripe md/raid5: pass gfp_t arg to grow_one_stripe() md/raid5: introduce configuration option rmw_level md/raid5: activate raid6 rmw feature md/raid6 algorithms: xor_syndrome() for SSE2 md/raid6 algorithms: xor_syndrome() for generic int md/raid6 algorithms: improve test program md/raid6 algorithms: delta syndrome functions raid5: handle expansion/resync case with stripe batching raid5: handle io error of batch list RAID5: batch adjacent full stripe write raid5: track overwrite disk count raid5: add a new flag to track if a stripe can be batched raid5: use flex_array for scribble data md raid0: access mddev->queue (request queue member) conditionally because it is not set when accessed from dm-raid md: allow resync to go faster when there is competing IO. md: remove 'go_faster' option from ->sync_request() ...
coccinelle.txt
Copyright 2010 Nicolas Palix <npalix@diku.dk>
Copyright 2010 Julia Lawall <julia@diku.dk>
Copyright 2010 Gilles Muller <Gilles.Muller@lip6.fr>
Getting Coccinelle
~~~~~~~~~~~~~~~~~~~~
The semantic patches included in the kernel use features and options
which are provided by Coccinelle version 1.0.0-rc11 and above.
Using earlier versions will fail as the option names used by
the Coccinelle files and coccicheck have been updated.
Coccinelle is available through the package manager
of many distributions, e.g. :
- Debian
- Fedora
- Ubuntu
- OpenSUSE
- Arch Linux
- NetBSD
- FreeBSD
You can get the latest version released from the Coccinelle homepage at
http://coccinelle.lip6.fr/
Information and tips about Coccinelle are also provided on the wiki
pages at http://cocci.ekstranet.diku.dk/wiki/doku.php
Once you have it, run the following command:
./configure
make
as a regular user, and install it with
sudo make install
Using Coccinelle on the Linux kernel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A Coccinelle-specific target is defined in the top level
Makefile. This target is named 'coccicheck' and calls the 'coccicheck'
front-end in the 'scripts' directory.
Four basic modes are defined: patch, report, context, and org. The mode to
use is specified by setting the MODE variable with 'MODE=<mode>'.
'patch' proposes a fix, when possible.
'report' generates a list in the following format:
file:line:column-column: message
'context' highlights lines of interest and their context in a
diff-like style.Lines of interest are indicated with '-'.
'org' generates a report in the Org mode format of Emacs.
Note that not all semantic patches implement all modes. For easy use
of Coccinelle, the default mode is "report".
Two other modes provide some common combinations of these modes.
'chain' tries the previous modes in the order above until one succeeds.
'rep+ctxt' runs successively the report mode and the context mode.
It should be used with the C option (described later)
which checks the code on a file basis.
Examples:
To make a report for every semantic patch, run the following command:
make coccicheck MODE=report
To produce patches, run:
make coccicheck MODE=patch
The coccicheck target applies every semantic patch available in the
sub-directories of 'scripts/coccinelle' to the entire Linux kernel.
For each semantic patch, a commit message is proposed. It gives a
description of the problem being checked by the semantic patch, and
includes a reference to Coccinelle.
As any static code analyzer, Coccinelle produces false
positives. Thus, reports must be carefully checked, and patches
reviewed.
To enable verbose messages set the V= variable, for example:
make coccicheck MODE=report V=1
By default, coccicheck tries to run as parallel as possible. To change
the parallelism, set the J= variable. For example, to run across 4 CPUs:
make coccicheck MODE=report J=4
Using Coccinelle with a single semantic patch
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The optional make variable COCCI can be used to check a single
semantic patch. In that case, the variable must be initialized with
the name of the semantic patch to apply.
For instance:
make coccicheck COCCI=<my_SP.cocci> MODE=patch
or
make coccicheck COCCI=<my_SP.cocci> MODE=report
Controlling Which Files are Processed by Coccinelle
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
By default the entire kernel source tree is checked.
To apply Coccinelle to a specific directory, M= can be used.
For example, to check drivers/net/wireless/ one may write:
make coccicheck M=drivers/net/wireless/
To apply Coccinelle on a file basis, instead of a directory basis, the
following command may be used:
make C=1 CHECK="scripts/coccicheck"
To check only newly edited code, use the value 2 for the C flag, i.e.
make C=2 CHECK="scripts/coccicheck"
In these modes, which works on a file basis, there is no information
about semantic patches displayed, and no commit message proposed.
This runs every semantic patch in scripts/coccinelle by default. The
COCCI variable may additionally be used to only apply a single
semantic patch as shown in the previous section.
The "report" mode is the default. You can select another one with the
MODE variable explained above.
Additional flags
~~~~~~~~~~~~~~~~~~
Additional flags can be passed to spatch through the SPFLAGS
variable.
make SPFLAGS=--use-glimpse coccicheck
make SPFLAGS=--use-idutils coccicheck
See spatch --help to learn more about spatch options.
Note that the '--use-glimpse' and '--use-idutils' options
require external tools for indexing the code. None of them is
thus active by default. However, by indexing the code with
one of these tools, and according to the cocci file used,
spatch could proceed the entire code base more quickly.
Proposing new semantic patches
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
New semantic patches can be proposed and submitted by kernel
developers. For sake of clarity, they should be organized in the
sub-directories of 'scripts/coccinelle/'.
Detailed description of the 'report' mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'report' generates a list in the following format:
file:line:column-column: message
Example:
Running
make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
will execute the following part of the SmPL script.
<smpl>
@r depends on !context && !patch && (org || report)@
expression x;
position p;
@@
ERR_PTR@p(PTR_ERR(x))
@script:python depends on report@
p << r.p;
x << r.x;
@@
msg="ERR_CAST can be used with %s" % (x)
coccilib.report.print_report(p[0], msg)
</smpl>
This SmPL excerpt generates entries on the standard output, as
illustrated below:
/home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
/home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
/home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg
Detailed description of the 'patch' mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When the 'patch' mode is available, it proposes a fix for each problem
identified.
Example:
Running
make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci
will execute the following part of the SmPL script.
<smpl>
@ depends on !context && patch && !org && !report @
expression x;
@@
- ERR_PTR(PTR_ERR(x))
+ ERR_CAST(x)
</smpl>
This SmPL excerpt generates patch hunks on the standard output, as
illustrated below:
diff -u -p a/crypto/ctr.c b/crypto/ctr.c
--- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
+++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
@@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
CRYPTO_ALG_TYPE_MASK);
if (IS_ERR(alg))
- return ERR_PTR(PTR_ERR(alg));
+ return ERR_CAST(alg);
/* Block size must be >= 4 bytes. */
err = -EINVAL;
Detailed description of the 'context' mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'context' highlights lines of interest and their context
in a diff-like style.
NOTE: The diff-like output generated is NOT an applicable patch. The
intent of the 'context' mode is to highlight the important lines
(annotated with minus, '-') and gives some surrounding context
lines around. This output can be used with the diff mode of
Emacs to review the code.
Example:
Running
make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
will execute the following part of the SmPL script.
<smpl>
@ depends on context && !patch && !org && !report@
expression x;
@@
* ERR_PTR(PTR_ERR(x))
</smpl>
This SmPL excerpt generates diff hunks on the standard output, as
illustrated below:
diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
--- /home/user/linux/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
+++ /tmp/nothing
@@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
CRYPTO_ALG_TYPE_MASK);
if (IS_ERR(alg))
- return ERR_PTR(PTR_ERR(alg));
/* Block size must be >= 4 bytes. */
err = -EINVAL;
Detailed description of the 'org' mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'org' generates a report in the Org mode format of Emacs.
Example:
Running
make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
will execute the following part of the SmPL script.
<smpl>
@r depends on !context && !patch && (org || report)@
expression x;
position p;
@@
ERR_PTR@p(PTR_ERR(x))
@script:python depends on org@
p << r.p;
x << r.x;
@@
msg="ERR_CAST can be used with %s" % (x)
msg_safe=msg.replace("[","@(").replace("]",")")
coccilib.org.print_todo(p[0], msg_safe)
</smpl>
This SmPL excerpt generates Org entries on the standard output, as
illustrated below:
* TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
* TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
* TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]
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