On 2.10.2018 23:44, Steven Rostedt wrote:
> On Mon, 1 Oct 2018 16:59:17 +0300
> Yordan Karadzhov <ykaradzhov@xxxxxxxxxx> wrote:
>
>> From: "Yordan Karadzhov (VMware)" <y.karadz@xxxxxxxxx>
>>
>> The kshark_get_X_easy() functions allow for an easy access to the
>> tep_record's fields. Using these functions can be inefficient if you
>> need access to more than one of the fields of the record.
>>
>> Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@xxxxxxxxx>
>> ---
>> kernel-shark-qt/src/libkshark.c | 185 ++++++++++++++++++++++++++++++++
>> kernel-shark-qt/src/libkshark.h | 12 +++
>> 2 files changed, 197 insertions(+)
>>
>> diff --git a/kernel-shark-qt/src/libkshark.c b/kernel-shark-qt/src/libkshark.c
>> index 506511d..a7983eb 100644
>> --- a/kernel-shark-qt/src/libkshark.c
>> +++ b/kernel-shark-qt/src/libkshark.c
>> @@ -888,6 +888,191 @@ static const char *kshark_get_info(struct tep_handle *pe,
>> return seq.buffer;
>> }
>>
>> +/**
>> + * @brief This function allows for an easy access to the original value of the
>> + * Process Id as recorded in the tep_record object. The record is read
>> + * from the file only in the case of an entry being touched by a plugin.
>> + * Be aware that using the kshark_get_X_easy functions can be
>> + * inefficient if you need an access to more than one of the data fields
>> + * of the record.
>> + *
>> + * @param entry: Input location for the KernelShark entry.
>> + *
>> + * @returns The original value of the Process Id as recorded in the
>> + * tep_record object on success, otherwise negative error code.
>> + */
>> +int kshark_get_pid_easy(struct kshark_entry *entry)
>> +{
>> + struct kshark_context *kshark_ctx = NULL;
>> + struct tep_record *data;
>> + int pid;
>> +
>> + if (!kshark_instance(&kshark_ctx))
>> + return -EFAULT;
>
> Perhaps this should return -ENODEV;
>
>> +
>> + if (entry->visible & KS_PLUGIN_UNTOUCHED_MASK) {
>
> What's the "UNTOUCHED_MASK" mean?
We use the KS_PLUGIN_UNTOUCHED_MASK to check the flag (bit)
which indicates if the entry has been touched and potential modified by
a plugin callback function. If the bit is set this means untouched.
This flag (bit) gets set when we load the data ( libkshark.c /
get_records())
entry->visible = 0xFF;
...
/* Execute all plugin-provided actions (if any). */
evt_handler = kshark_ctx->event_handlers;
while ((evt_handler = kshark_find_event_handler(evt_handler,
entry->event_id))) {
evt_handler->event_func(kshark_ctx, rec, entry);
evt_handler = evt_handler->next;
if (!evt_handler)
entry->visible &= ~KS_PLUGIN_UNTOUCHED_MASK;
}
>
>> + pid = entry->pid;
>> + } else {
In this case the entry has been touched by a plugin. Because of this we
do not trust the value of "entry->pid".
>> + data = kshark_read_at(kshark_ctx, entry->offset);
>> + pid = tep_data_pid(kshark_ctx->pevent, data);
>> + free_record(data);
>
> Would it be possible to do:
>
> entry->visible |= KS_PLUGIN_UNTOUCHED_MASK;
> entry->pid = pid;
>
> ?
>
> Of course this depends on what that mask means.
>
>> + }
>> +
>> + return pid;
>> +}
>> +
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