* Re: [PATCH] ntb_tool: Fix infinite loop bug when writing spad/peer_spad file
[not found] <1464381511-18491-1-git-send-email-logang@deltatee.com>
@ 2016-05-28 13:09 ` Allen Hubbe
2016-06-04 15:19 ` Jon Mason
0 siblings, 1 reply; 2+ messages in thread
From: Allen Hubbe @ 2016-05-28 13:09 UTC (permalink / raw)
To: Logan Gunthorpe; +Cc: Jon Mason, Dave Jiang, linux-ntb, linux-kernel
On Fri, May 27, 2016 at 4:38 PM, Logan Gunthorpe <logang@deltatee.com> wrote:
> If you tried to write two spads in one line, as per the example:
>
> root@peer# echo '0 0x01010101 1 0x7f7f7f7f' > $DBG_DIR/peer_spad
>
> then the CPU would freeze in an infinite loop.
>
> This wasn't immediately obvious but 'pos' was not incrementing the
> buffer, so after reading the second pair of values, 'pos' would once
> again be 3 and it would re-read the second pair of values ad infinitum.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Good catch. Thanks Logan.
Acked-by: Allen Hubbe <Allen.Hubbe@emc.com>
> ---
> drivers/ntb/test/ntb_tool.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
> index 6f5dc6c..209ef7c 100644
> --- a/drivers/ntb/test/ntb_tool.c
> +++ b/drivers/ntb/test/ntb_tool.c
> @@ -268,7 +268,7 @@ static ssize_t tool_spadfn_write(struct tool_ctx *tc,
> {
> int spad_idx;
> u32 spad_val;
> - char *buf;
> + char *buf, *buf_ptr;
> int pos, n;
> ssize_t rc;
>
> @@ -288,14 +288,15 @@ static ssize_t tool_spadfn_write(struct tool_ctx *tc,
> }
>
> buf[size] = 0;
> -
> - n = sscanf(buf, "%d %i%n", &spad_idx, &spad_val, &pos);
> + buf_ptr = buf;
> + n = sscanf(buf_ptr, "%d %i%n", &spad_idx, &spad_val, &pos);
> while (n == 2) {
> + buf_ptr += pos;
> rc = spad_write_fn(tc->ntb, spad_idx, spad_val);
> if (rc)
> break;
>
> - n = sscanf(buf + pos, "%d %i%n", &spad_idx, &spad_val, &pos);
> + n = sscanf(buf_ptr, "%d %i%n", &spad_idx, &spad_val, &pos);
> }
>
> if (n < 0)
> --
> 2.1.4
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] ntb_tool: Fix infinite loop bug when writing spad/peer_spad file
2016-05-28 13:09 ` [PATCH] ntb_tool: Fix infinite loop bug when writing spad/peer_spad file Allen Hubbe
@ 2016-06-04 15:19 ` Jon Mason
0 siblings, 0 replies; 2+ messages in thread
From: Jon Mason @ 2016-06-04 15:19 UTC (permalink / raw)
To: Allen Hubbe; +Cc: Logan Gunthorpe, Dave Jiang, linux-ntb, linux-kernel
On Sat, May 28, 2016 at 9:09 AM, Allen Hubbe <allenbh@gmail.com> wrote:
> On Fri, May 27, 2016 at 4:38 PM, Logan Gunthorpe <logang@deltatee.com> wrote:
>> If you tried to write two spads in one line, as per the example:
>>
>> root@peer# echo '0 0x01010101 1 0x7f7f7f7f' > $DBG_DIR/peer_spad
>>
>> then the CPU would freeze in an infinite loop.
>>
>> This wasn't immediately obvious but 'pos' was not incrementing the
>> buffer, so after reading the second pair of values, 'pos' would once
>> again be 3 and it would re-read the second pair of values ad infinitum.
>>
>> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
>
> Good catch. Thanks Logan.
>
> Acked-by: Allen Hubbe <Allen.Hubbe@emc.com>
Applied to the ntb branch
Thanks,
Jon
>> ---
>> drivers/ntb/test/ntb_tool.c | 9 +++++----
>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
>> index 6f5dc6c..209ef7c 100644
>> --- a/drivers/ntb/test/ntb_tool.c
>> +++ b/drivers/ntb/test/ntb_tool.c
>> @@ -268,7 +268,7 @@ static ssize_t tool_spadfn_write(struct tool_ctx *tc,
>> {
>> int spad_idx;
>> u32 spad_val;
>> - char *buf;
>> + char *buf, *buf_ptr;
>> int pos, n;
>> ssize_t rc;
>>
>> @@ -288,14 +288,15 @@ static ssize_t tool_spadfn_write(struct tool_ctx *tc,
>> }
>>
>> buf[size] = 0;
>> -
>> - n = sscanf(buf, "%d %i%n", &spad_idx, &spad_val, &pos);
>> + buf_ptr = buf;
>> + n = sscanf(buf_ptr, "%d %i%n", &spad_idx, &spad_val, &pos);
>> while (n == 2) {
>> + buf_ptr += pos;
>> rc = spad_write_fn(tc->ntb, spad_idx, spad_val);
>> if (rc)
>> break;
>>
>> - n = sscanf(buf + pos, "%d %i%n", &spad_idx, &spad_val, &pos);
>> + n = sscanf(buf_ptr, "%d %i%n", &spad_idx, &spad_val, &pos);
>> }
>>
>> if (n < 0)
>> --
>> 2.1.4
^ permalink raw reply [flat|nested] 2+ messages in thread
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2016-05-28 13:09 ` [PATCH] ntb_tool: Fix infinite loop bug when writing spad/peer_spad file Allen Hubbe
2016-06-04 15:19 ` Jon Mason
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