Re: [PATCH v9 0/4] Uprobes: Support SDT markers having reference count (semaphore)

From: Naveen N. Rao
Date: Tue Aug 21 2018 - 03:34:31 EST

Song Liu wrote:
I am testing the patch set with the following code:

#include <stdio.h>
#include <unistd.h>

volatile short semaphore = 0;

int for_uprobe(int c)
printf("%d\n", c + 10);
return c + 1;

int main(int argc, char *argv[])
while (1) {
printf("semaphore %d\n", semaphore);

I created a uprobe on function for_uprobe(), that uses semaphore as
reference counter:

echo "p:uprobe_1 /root/a.out:0x49a(0x1036)" >> uprobe_events

Is that even valid? That _looks_ like a semaphore, but I'm not quite sure that it qualifies as an _SDT_ semaphore. Do you see this issue if you instead use the macros provided by <sys/sdt.h> to create SDT markers?

- Naveen