diff options
Diffstat (limited to 'Documentation/DocBook')
| -rw-r--r-- | Documentation/DocBook/Makefile | 2 | ||||
| -rw-r--r-- | Documentation/DocBook/debugobjects.tmpl | 391 | ||||
| -rw-r--r-- | Documentation/DocBook/kgdb.tmpl | 8 | ||||
| -rw-r--r-- | Documentation/DocBook/rapidio.tmpl | 1 |
4 files changed, 397 insertions, 5 deletions
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index 83966e94cc32..0eb0d027eb32 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -12,7 +12,7 @@ DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \ kernel-api.xml filesystems.xml lsm.xml usb.xml kgdb.xml \ gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \ genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \ - mac80211.xml + mac80211.xml debugobjects.xml ### # The build process is as follows (targets): diff --git a/Documentation/DocBook/debugobjects.tmpl b/Documentation/DocBook/debugobjects.tmpl new file mode 100644 index 000000000000..7f5f218015fe --- /dev/null +++ b/Documentation/DocBook/debugobjects.tmpl @@ -0,0 +1,391 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" + "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> + +<book id="debug-objects-guide"> + <bookinfo> + <title>Debug objects life time</title> + + <authorgroup> + <author> + <firstname>Thomas</firstname> + <surname>Gleixner</surname> + <affiliation> + <address> + <email>[email protected]</email> + </address> + </affiliation> + </author> + </authorgroup> + + <copyright> + <year>2008</year> + <holder>Thomas Gleixner</holder> + </copyright> + + <legalnotice> + <para> + This documentation is free software; you can redistribute + it and/or modify it under the terms of the GNU General Public + License version 2 as published by the Free Software Foundation. + </para> + + <para> + This program is distributed in the hope that it will be + useful, but WITHOUT ANY WARRANTY; without even the implied + warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + See the GNU General Public License for more details. + </para> + + <para> + You should have received a copy of the GNU General Public + License along with this program; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, + MA 02111-1307 USA + </para> + + <para> + For more details see the file COPYING in the source + distribution of Linux. + </para> + </legalnotice> + </bookinfo> + +<toc></toc> + + <chapter id="intro"> + <title>Introduction</title> + <para> + debugobjects is a generic infrastructure to track the life time + of kernel objects and validate the operations on those. + </para> + <para> + debugobjects is useful to check for the following error patterns: + <itemizedlist> + <listitem><para>Activation of uninitialized objects</para></listitem> + <listitem><para>Initialization of active objects</para></listitem> + <listitem><para>Usage of freed/destroyed objects</para></listitem> + </itemizedlist> + </para> + <para> + debugobjects is not changing the data structure of the real + object so it can be compiled in with a minimal runtime impact + and enabled on demand with a kernel command line option. + </para> + </chapter> + + <chapter id="howto"> + <title>Howto use debugobjects</title> + <para> + A kernel subsystem needs to provide a data structure which + describes the object type and add calls into the debug code at + appropriate places. The data structure to describe the object + type needs at minimum the name of the object type. Optional + functions can and should be provided to fixup detected problems + so the kernel can continue to work and the debug information can + be retrieved from a live system instead of hard core debugging + with serial consoles and stack trace transcripts from the + monitor. + </para> + <para> + The debug calls provided by debugobjects are: + <itemizedlist> + <listitem><para>debug_object_init</para></listitem> + <listitem><para>debug_object_init_on_stack</para></listitem> + <listitem><para>debug_object_activate</para></listitem> + <listitem><para>debug_object_deactivate</para></listitem> + <listitem><para>debug_object_destroy</para></listitem> + <listitem><para>debug_object_free</para></listitem> + </itemizedlist> + Each of these functions takes the address of the real object and + a pointer to the object type specific debug description + structure. + </para> + <para> + Each detected error is reported in the statistics and a limited + number of errors are printk'ed including a full stack trace. + </para> + <para> + The statistics are available via debugfs/debug_objects/stats. + They provide information about the number of warnings and the + number of successful fixups along with information about the + usage of the internal tracking objects and the state of the + internal tracking objects pool. + </para> + </chapter> + <chapter id="debugfunctions"> + <title>Debug functions</title> + <sect1 id="prototypes"> + <title>Debug object function reference</title> +!Elib/debugobjects.c + </sect1> + <sect1 id="debug_object_init"> + <title>debug_object_init</title> + <para> + This function is called whenever the initialization function + of a real object is called. + </para> + <para> + When the real object is already tracked by debugobjects it is + checked, whether the object can be initialized. Initializing + is not allowed for active and destroyed objects. When + debugobjects detects an error, then it calls the fixup_init + function of the object type description structure if provided + by the caller. The fixup function can correct the problem + before the real initialization of the object happens. E.g. it + can deactivate an active object in order to prevent damage to + the subsystem. + </para> + <para> + When the real object is not yet tracked by debugobjects, + debugobjects allocates a tracker object for the real object + and sets the tracker object state to ODEBUG_STATE_INIT. It + verifies that the object is not on the callers stack. If it is + on the callers stack then a limited number of warnings + including a full stack trace is printk'ed. The calling code + must use debug_object_init_on_stack() and remove the object + before leaving the function which allocated it. See next + section. + </para> + </sect1> + + <sect1 id="debug_object_init_on_stack"> + <title>debug_object_init_on_stack</title> + <para> + This function is called whenever the initialization function + of a real object which resides on the stack is called. + </para> + <para> + When the real object is already tracked by debugobjects it is + checked, whether the object can be initialized. Initializing + is not allowed for active and destroyed objects. When + debugobjects detects an error, then it calls the fixup_init + function of the object type description structure if provided + by the caller. The fixup function can correct the problem + before the real initialization of the object happens. E.g. it + can deactivate an active object in order to prevent damage to + the subsystem. + </para> + <para> + When the real object is not yet tracked by debugobjects + debugobjects allocates a tracker object for the real object + and sets the tracker object state to ODEBUG_STATE_INIT. It + verifies that the object is on the callers stack. + </para> + <para> + An object which is on the stack must be removed from the + tracker by calling debug_object_free() before the function + which allocates the object returns. Otherwise we keep track of + stale objects. + </para> + </sect1> + + <sect1 id="debug_object_activate"> + <title>debug_object_activate</title> + <para> + This function is called whenever the activation function of a + real object is called. + </para> + <para> + When the real object is already tracked by debugobjects it is + checked, whether the object can be activated. Activating is + not allowed for active and destroyed objects. When + debugobjects detects an error, then it calls the + fixup_activate function of the object type description + structure if provided by the caller. The fixup function can + correct the problem before the real activation of the object + happens. E.g. it can deactivate an active object in order to + prevent damage to the subsystem. + </para> + <para> + When the real object is not yet tracked by debugobjects then + the fixup_activate function is called if available. This is + necessary to allow the legitimate activation of statically + allocated and initialized objects. The fixup function checks + whether the object is valid and calls the debug_objects_init() + function to initialize the tracking of this object. + </para> + <para> + When the activation is legitimate, then the state of the + associated tracker object is set to ODEBUG_STATE_ACTIVE. + </para> + </sect1> + + <sect1 id="debug_object_deactivate"> + <title>debug_object_deactivate</title> + <para> + This function is called whenever the deactivation function of + a real object is called. + </para> + <para> + When the real object is tracked by debugobjects it is checked, + whether the object can be deactivated. Deactivating is not + allowed for untracked or destroyed objects. + </para> + <para> + When the deactivation is legitimate, then the state of the + associated tracker object is set to ODEBUG_STATE_INACTIVE. + </para> + </sect1> + + <sect1 id="debug_object_destroy"> + <title>debug_object_destroy</title> + <para> + This function is called to mark an object destroyed. This is + useful to prevent the usage of invalid objects, which are + still available in memory: either statically allocated objects + or objects which are freed later. + </para> + <para> + When the real object is tracked by debugobjects it is checked, + whether the object can be destroyed. Destruction is not + allowed for active and destroyed objects. When debugobjects + detects an error, then it calls the fixup_destroy function of + the object type description structure if provided by the + caller. The fixup function can correct the problem before the + real destruction of the object happens. E.g. it can deactivate + an active object in order to prevent damage to the subsystem. + </para> + <para> + When the destruction is legitimate, then the state of the + associated tracker object is set to ODEBUG_STATE_DESTROYED. + </para> + </sect1> + + <sect1 id="debug_object_free"> + <title>debug_object_free</title> + <para> + This function is called before an object is freed. + </para> + <para> + When the real object is tracked by debugobjects it is checked, + whether the object can be freed. Free is not allowed for + active objects. When debugobjects detects an error, then it + calls the fixup_free function of the object type description + structure if provided by the caller. The fixup function can + correct the problem before the real free of the object + happens. E.g. it can deactivate an active object in order to + prevent damage to the subsystem. + </para> + <para> + Note that debug_object_free removes the object from the + tracker. Later usage of the object is detected by the other + debug checks. + </para> + </sect1> + </chapter> + <chapter id="fixupfunctions"> + <title>Fixup functions</title> + <sect1 id="debug_obj_descr"> + <title>Debug object type description structure</title> +!Iinclude/linux/debugobjects.h + </sect1> + <sect1 id="fixup_init"> + <title>fixup_init</title> + <para> + This function is called from the debug code whenever a problem + in debug_object_init is detected. The function takes the + address of the object and the state which is currently + recorded in the tracker. + </para> + <para> + Called from debug_object_init when the object state is: + <itemizedlist> + <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem> + </itemizedlist> + </para> + <para> + The function returns 1 when the fixup was successful, + otherwise 0. The return value is used to update the + statistics. + </para> + <para> + Note, that the function needs to call the debug_object_init() + function again, after the damage has been repaired in order to + keep the state consistent. + </para> + </sect1> + + <sect1 id="fixup_activate"> + <title>fixup_activate</title> + <para> + This function is called from the debug code whenever a problem + in debug_object_activate is detected. + </para> + <para> + Called from debug_object_activate when the object state is: + <itemizedlist> + <listitem><para>ODEBUG_STATE_NOTAVAILABLE</para></listitem> + <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem> + </itemizedlist> + </para> + <para> + The function returns 1 when the fixup was successful, + otherwise 0. The return value is used to update the + statistics. + </para> + <para> + Note that the function needs to call the debug_object_activate() + function again after the damage has been repaired in order to + keep the state consistent. + </para> + <para> + The activation of statically initialized objects is a special + case. When debug_object_activate() has no tracked object for + this object address then fixup_activate() is called with + object state ODEBUG_STATE_NOTAVAILABLE. The fixup function + needs to check whether this is a legitimate case of a + statically initialized object or not. In case it is it calls + debug_object_init() and debug_object_activate() to make the + object known to the tracker and marked active. In this case + the function should return 0 because this is not a real fixup. + </para> + </sect1> + + <sect1 id="fixup_destroy"> + <title>fixup_destroy</title> + <para> + This function is called from the debug code whenever a problem + in debug_object_destroy is detected. + </para> + <para> + Called from debug_object_destroy when the object state is: + <itemizedlist> + <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem> + </itemizedlist> + </para> + <para> + The function returns 1 when the fixup was successful, + otherwise 0. The return value is used to update the + statistics. + </para> + </sect1> + <sect1 id="fixup_free"> + <title>fixup_free</title> + <para> + This function is called from the debug code whenever a problem + in debug_object_free is detected. Further it can be called + from the debug checks in kfree/vfree, when an active object is + detected from the debug_check_no_obj_freed() sanity checks. + </para> + <para> + Called from debug_object_free() or debug_check_no_obj_freed() + when the object state is: + <itemizedlist> + <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem> + </itemizedlist> + </para> + <para> + The function returns 1 when the fixup was successful, + otherwise 0. The return value is used to update the + statistics. + </para> + </sect1> + </chapter> + <chapter id="bugs"> + <title>Known Bugs And Assumptions</title> + <para> + None (knock on wood). + </para> + </chapter> +</book> diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl index 97618bed4d65..028a8444d95e 100644 --- a/Documentation/DocBook/kgdb.tmpl +++ b/Documentation/DocBook/kgdb.tmpl @@ -72,7 +72,7 @@ kgdb is a source level debugger for linux kernel. It is used along with gdb to debug a linux kernel. The expectation is that gdb can be used to "break in" to the kernel to inspect memory, variables - and look through a cal stack information similar to what an + and look through call stack information similar to what an application developer would use gdb for. It is possible to place breakpoints in kernel code and perform some limited execution stepping. @@ -93,8 +93,10 @@ <chapter id="CompilingAKernel"> <title>Compiling a kernel</title> <para> - To enable <symbol>CONFIG_KGDB</symbol>, look under the "Kernel debugging" - and then select "KGDB: kernel debugging with remote gdb". + To enable <symbol>CONFIG_KGDB</symbol> you should first turn on + "Prompt for development and/or incomplete code/drivers" + (CONFIG_EXPERIMENTAL) in "General setup", then under the + "Kernel debugging" select "KGDB: kernel debugging with remote gdb". </para> <para> Next you should choose one of more I/O drivers to interconnect debugging diff --git a/Documentation/DocBook/rapidio.tmpl b/Documentation/DocBook/rapidio.tmpl index b9e143e28c64..54eb26b57372 100644 --- a/Documentation/DocBook/rapidio.tmpl +++ b/Documentation/DocBook/rapidio.tmpl @@ -133,7 +133,6 @@ !Idrivers/rapidio/rio-sysfs.c </sect1> <sect1 id="PPC32_support"><title>PPC32 support</title> -!Iarch/powerpc/kernel/rio.c !Earch/powerpc/sysdev/fsl_rio.c !Iarch/powerpc/sysdev/fsl_rio.c </sect1> |