[PATCH] --dump-dmesg fix for post 3.5 kernels

[Bouchard Louis]

Hello,

Le 04/02/2013 09:27, Atsushi Kumagai a écrit :
> Hello Louis,
> 
> On Thu, 31 Jan 2013 12:48:08 +0100
> Louis Bouchard <louis.bouchard at canonical.com> wrote:
> 
>>        This patch enable the --dump-dmesg functionality that
>>        was broken with post 3.5 kernel which use the variable-length
>>        record format for the kernel log buffer.
> 
> I appreciate your hard work.
> Your patch seems to work correctly, but I have some comments.
> (You don't need to resend the patch.)
> 

Thanks. It was a very useful learning experience, especially for my
debian packaging tasks.

>>
>> Signed-off-by: Louis Bouchard <louis.bouchard at canonical.com>
>> ---
>>  makedumpfile.c |  242 +++++++++++++++++++++++++++++++++++++++++++++-----------
>>  makedumpfile.h |   16 ++++
>>  2 files changed, 213 insertions(+), 45 deletions(-)
>>
>> diff --git a/makedumpfile.c b/makedumpfile.c
>> index 715ca6e..a5180f6 100644
>> --- a/makedumpfile.c
>> +++ b/makedumpfile.c
>> @@ -20,6 +20,7 @@
>>  #include "erase_info.h"
>>  #include "sadump_info.h"
>>  #include <stddef.h>
>> +#include <ctype.h>
>>  #include <sys/time.h>
>>  
>>  struct symbol_table	symbol_table;
>> @@ -848,6 +849,8 @@ get_symbol_info(void)
>>  	SYMBOL_INIT(log_buf, "log_buf");
>>  	SYMBOL_INIT(log_buf_len, "log_buf_len");
>>  	SYMBOL_INIT(log_end, "log_end");
>> +	SYMBOL_INIT(log_first_idx, "log_first_idx");
>> +	SYMBOL_INIT(log_next_idx, "log_next_idx");
>>  	SYMBOL_INIT(max_pfn, "max_pfn");
>>  	SYMBOL_INIT(modules, "modules");
>>  	SYMBOL_INIT(high_memory, "high_memory");
>> @@ -1176,6 +1179,13 @@ get_structure_info(void)
>>  	OFFSET_INIT(elf64_phdr.p_paddr, "elf64_phdr", "p_paddr");
>>  	OFFSET_INIT(elf64_phdr.p_memsz, "elf64_phdr", "p_memsz");
>>  
>> +	SIZE_INIT(log, "log");
>> +	OFFSET_INIT(log.ts_nsec, "log", "ts_nsec");
>> +	OFFSET_INIT(log.len, "log", "len");
>> +	OFFSET_INIT(log.text_len, "log", "text_len");
>> +	OFFSET_INIT(log.dict_len, "log", "dict_len");
>> +	OFFSET_INIT(log.dict_len, "log", "level");
>> +
> 
> Why you overwrite log.dict_len with log.level ?
> And is log.dict_len necessary for this feature ?
> 

Sorry, this is a leftover from my log-level hack. The rest of the code
has been removed, so this should be removed as well.

>>  	return TRUE;
>>  }
>>  
>> @@ -1354,6 +1364,8 @@ write_vmcoreinfo_data(void)
>>  	WRITE_SYMBOL("log_buf", log_buf);
>>  	WRITE_SYMBOL("log_buf_len", log_buf_len);
>>  	WRITE_SYMBOL("log_end", log_end);
>> +	WRITE_SYMBOL("log_first_idx", log_first_idx);
>> +	WRITE_SYMBOL("log_next_idx", log_next_idx);
>>  	WRITE_SYMBOL("max_pfn", max_pfn);
>>  	WRITE_SYMBOL("high_memory", high_memory);
>>  	WRITE_SYMBOL("node_remap_start_vaddr", node_remap_start_vaddr);
>> @@ -1404,6 +1416,10 @@ write_vmcoreinfo_data(void)
>>  	WRITE_MEMBER_OFFSET("node_memblk_s.size", node_memblk_s.size);
>>  	WRITE_MEMBER_OFFSET("node_memblk_s.nid", node_memblk_s.nid);
>>  	WRITE_MEMBER_OFFSET("vm_struct.addr", vm_struct.addr);
>> +	WRITE_MEMBER_OFFSET("log.ts_nsec",log.ts_nsec);
>> +	WRITE_MEMBER_OFFSET("log.len",log.len);
>> +	WRITE_MEMBER_OFFSET("log.text_len",log.text_len);
>> +	WRITE_MEMBER_OFFSET("log.dict_len",log.dict_len);
>>  
>>  	if (SYMBOL(node_data) != NOT_FOUND_SYMBOL)
>>  		WRITE_ARRAY_LENGTH("node_data", node_data);
>> @@ -1664,6 +1680,8 @@ read_vmcoreinfo(void)
>>  	READ_SYMBOL("log_buf", log_buf);
>>  	READ_SYMBOL("log_buf_len", log_buf_len);
>>  	READ_SYMBOL("log_end", log_end);
>> +	READ_SYMBOL("log_first_idx",log_first_idx);
>> +	READ_SYMBOL("log_next_idx",log_next_idx);
>>  	READ_SYMBOL("max_pfn", max_pfn);
>>  	READ_SYMBOL("high_memory", high_memory);
>>  	READ_SYMBOL("node_remap_start_vaddr", node_remap_start_vaddr);
>> @@ -1679,6 +1697,7 @@ read_vmcoreinfo(void)
>>  	READ_STRUCTURE_SIZE("node_memblk_s", node_memblk_s);
>>  	READ_STRUCTURE_SIZE("nodemask_t", nodemask_t);
>>  	READ_STRUCTURE_SIZE("pageflags", pageflags);
>> +	READ_STRUCTURE_SIZE("log", log);
> 
> You forgot to add "WRITE_STRUCTURE_SIZE("log", log)", I'll add it.
> 
> Lastly, your patch causes the following warning:
> 
>   makedumpfile.c: In function 'dump_dmesg':
>   makedumpfile.c:3562: warning: 'log_end' may be used uninitialized in this function
> 
> So, I'll fix this patch with the change below:
> 
> 
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 2a2fcbd..ebedd07 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -1384,6 +1384,7 @@ write_vmcoreinfo_data(void)
> 	WRITE_STRUCTURE_SIZE("node_memblk_s", node_memblk_s);
> 	WRITE_STRUCTURE_SIZE("nodemask_t", nodemask_t);
> 	WRITE_STRUCTURE_SIZE("pageflags", pageflags);
> +	WRITE_STRUCTURE_SIZE("log", log);
> 
> 	/*
> 	 * write the member offset of 1st kernel
> @@ -3626,7 +3627,9 @@ dump_dmesg()
> 			}
> 			log_end = log_end_2_6_24;
> 		}
> -	}
> +	} else
> +		log_end = 0;
> +

Oups, I missed this one, sorry.

> 	if (!readmem(VADDR, SYMBOL(log_buf_len), &log_buf_len,
> 	    sizeof(log_buf_len))) {
> 		ERRMSG("Can't get log_buf_len.\n");
> 
> 
> Thanks
> Atsushi Kumagai
> 

This all looks fine. I am planning to add this patch over your 1.5.1
version for Debian/Sid so we get this working (I need it myself for the
upcoming Ubuntu/Raring) if you don't see any problem. The debian patch
will be removed in the next version when it makes it into your upstream
release.

I'll go pick up your patch in your repo as soon as it makes it in. Just
let me know when you commit if you have a chance.

Kind regards,

...Louis
-- 
Louis Bouchard
Backline Support Analyst
Canonical Ltd
Ubuntu support: http://landscape.canonical.com