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SubjectRe: [PATCH] pstore: reset ftrace_read_cnt at ramoops_pstore_open
On Tue  4.Mar'14 at 11:11:11 -0800, Kees Cook wrote:
>On Mon, Mar 3, 2014 at 5:40 PM, Liu ShuoX <shuox.liu@intel.com> wrote:
>> On Mon 3.Mar'14 at 11:45:59 -0800, Kees Cook wrote:
>>>
>>> On Thu, Feb 27, 2014 at 10:37 PM, <shuox.liu@intel.com> wrote:
>>>>
>>>> From: Liu ShuoX <shuox.liu@intel.com>
>>>>
>>>> ftrace_read_cnt need to be reset in open to support mutli times
>>>> getting the records.
>>>>
>>>> Signed-off-by: Liu ShuoX <shuox.liu@intel.com>
>>>> ---
>>>> fs/pstore/ram.c | 1 +
>>>> 1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
>>>> index fa8cef2..a5d0cab 100644
>>>> --- a/fs/pstore/ram.c
>>>> +++ b/fs/pstore/ram.c
>>>> @@ -101,6 +101,7 @@ static int ramoops_pstore_open(struct pstore_info
>>>> *psi)
>>>>
>>>> cxt->dump_read_cnt = 0;
>>>> cxt->console_read_cnt = 0;
>>>> + cxt->ftrace_read_cnt = 0;
>>>> return 0;
>>>> }
>>>
>>>
>>> I think we need a separate function for "clear" for the
>>> ramoops_context struct. IIUC, we're missing a similar initialization
>>> in ramoops_probe, which lacks both console_read_cnt=0 and
>>> ftrace_read_cnt=0. Then both places could call this?
>>
>> Hi Kees,
>> Currently, we have only one static ramoops_context named oops_cxt.
>> *_read_cnt should be initialized to 0 as default. Need we still add
>> such function for 'clear'?
>
>We have the pstore-global "oops_cxt" context. It is "initialized" only
>once in ramoops_probe (and seems to needlessly set dump_read_cnt to
>0). Otherwise, the context is initialized via ramoops_register_dummy
>from module parameters (and initialized to zero with kzalloc).
>
>So, I think my initial comment about "clear" is probably not right,
>but that ramoops_pstore_open should be doing that (i.e. your original
>patch is close). However, I think I'd like to see the needless zeroing
>in ramoops_probe removed, and the "variables that need clearing on
>open" documented in comments in "struct ramoops_context". That should
>make this code more clear to read next time. :)
Sorry for delay reply. How about below patch?

From: Liu ShuoX <shuox.liu@intel.com>

ftrace_read_cnt need to be reset in open to support mutli times
getting the records.

Signed-off-by: Liu ShuoX <shuox.liu@intel.com>
---
fs/pstore/ram.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index fa8cef2..9fe5b13 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -86,6 +86,7 @@ struct ramoops_context {
struct persistent_ram_ecc_info ecc_info;
unsigned int max_dump_cnt;
unsigned int dump_write_cnt;
+ /* _read_cnt need clear on ramoops_pstore_open */
unsigned int dump_read_cnt;
unsigned int console_read_cnt;
unsigned int ftrace_read_cnt;
@@ -101,6 +102,7 @@ static int ramoops_pstore_open(struct pstore_info *psi)

cxt->dump_read_cnt = 0;
cxt->console_read_cnt = 0;
+ cxt->ftrace_read_cnt = 0;
return 0;
}

@@ -428,7 +430,6 @@ static int ramoops_probe(struct platform_device *pdev)
if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);

- cxt->dump_read_cnt = 0;
cxt->size = pdata->mem_size;
cxt->phys_addr = pdata->mem_address;
cxt->record_size = pdata->record_size;
--
1.8.3.2


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