[PATCH v3 3/3] powerpc/xmon: add debugfs entry for xmon

[Guilherme G. Piccoli]

On 02/21/2017 03:35 AM, Pan Xinhui wrote:
> 
> 
> 在 2017/2/21 09:58, Guilherme G. Piccoli 写道:
>> Currently the xmon debugger is set only via kernel boot command-line.
>> It's disabled by default, and can be enabled with "xmon=on" on the
>> command-line. Also, xmon may be accessed via sysrq mechanism.
>> But we cannot enable/disable xmon in runtime, it needs kernel reload.
>>
>> This patch introduces a debugfs entry for xmon, allowing user to query
>> its current state and change it if desired. Basically, the "xmon" file
>> to read from/write to is under the debugfs mount point, on powerpc
>> directory. It's a simple attribute, value 0 meaning xmon is disabled
>> and value 1 the opposite. Writing these states to the file will take
>> immediate effect in the debugger.
>>
>> Signed-off-by: Guilherme G. Piccoli <gpiccoli at linux.vnet.ibm.com>
>> ---
>> v3: logic improved based in the changes made on patch 1.
>>
>> v2: dropped the custom parser by using simple attributes [mpe suggestion].
>>
>>
>>  arch/powerpc/xmon/xmon.c | 31 +++++++++++++++++++++++++++++++
>>  1 file changed, 31 insertions(+)
>>
>> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
>> index f1fcfa8..764ea62 100644
>> --- a/arch/powerpc/xmon/xmon.c
>> +++ b/arch/powerpc/xmon/xmon.c
>> @@ -29,6 +29,10 @@
>>  #include <linux/nmi.h>
>>  #include <linux/ctype.h>
>>
>> +#ifdef CONFIG_DEBUG_FS
>> +#include <linux/debugfs.h>
>> +#endif
>> +
>>  #include <asm/ptrace.h>
>>  #include <asm/string.h>
>>  #include <asm/prom.h>
>> @@ -3275,6 +3279,33 @@ static int __init setup_xmon_sysrq(void)
>>  device_initcall(setup_xmon_sysrq);
>>  #endif /* CONFIG_MAGIC_SYSRQ */
>>
>> +#ifdef CONFIG_DEBUG_FS
>> +static int xmon_dbgfs_set(void *data, u64 val)
>> +{
>> +	xmon_off = !val;
> xmon_off is really 'off' :)
> There is xmon_on
> 

OK, this is *really* odd.
I sent the wrong version of the patch ={

I'm _sorry_, thanks for noticing Xinhui!

@Michael, my complete fault. I tested the real "v3" of this patch, but
for some reason (aka my disorganization) I sent the old v2. In the v3, I
used "xmon_on = !!val".

How about if I resend the whole series tomorrow, correcting this and
changing patch 2 in order to keep the automatic show of backtrace
always? Or do you prefer to fix it yourself?

Thanks, and again, I apologize for the mess.


Guilherme



>> +	xmon_init(!xmon_off);
>> +
>> +	return 0;
>> +}
>> +
>> +static int xmon_dbgfs_get(void *data, u64 *val)
>> +{
>> +	*val = !xmon_off;
>> +	return 0;
>> +}
>> +
>> +DEFINE_SIMPLE_ATTRIBUTE(xmon_dbgfs_ops, xmon_dbgfs_get,
>> +			xmon_dbgfs_set, "%llu\n");
>> +
>> +static int __init setup_xmon_dbgfs(void)
>> +{
>> +	debugfs_create_file("xmon", 0600, powerpc_debugfs_root, NULL,
>> +				&xmon_dbgfs_ops);
>> +	return 0;
>> +}
>> +device_initcall(setup_xmon_dbgfs);
>> +#endif /* CONFIG_DEBUG_FS */
>> +
>>  static int xmon_early __initdata;
>>
>>  static int __init early_parse_xmon(char *p)
>>