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2013/6/3 Michael Ellerman <michael@xxxxxxxxxxxxxx>:
> I was hitting this on my system, where it's 65536. So fix the todo and
> read it from /proc.
>
> I left a fallback to the hardcoded values in case /proc is not mounted
> or something else goes wrong.

Looks good to me, but please also fclose() in read_pid_max().

> ---
>  include/pids.h |    1 +
>  pids.c         |   41 ++++++++++++++++++++++++++++++++++++-----
>  trinity.c      |    2 ++
>  3 files changed, 39 insertions(+), 5 deletions(-)
>
> diff --git a/include/pids.h b/include/pids.h
> index 6a19630..b93ec4c 100644
> --- a/include/pids.h
> +++ b/include/pids.h
> @@ -14,6 +14,7 @@ int find_pid_slot(pid_t mypid);
>  bool pidmap_empty(void);
>  void dump_pid_slots(void);
>  int pid_is_valid(pid_t);
> +void pids_init(void);
>
>  #define pid_alive(_pid) kill(_pid, 0)
>
> diff --git a/pids.c b/pids.c
> index 7b8a73b..cfdd5d8 100644
> --- a/pids.c
> +++ b/pids.c
> @@ -36,17 +36,48 @@ void dump_pid_slots(void)
>                 printf("## slot%d: %d\n", i, shm->pids[i]);
>  }
>
> -int pid_is_valid(pid_t pid)
> +static pid_t pidmax;
> +
> +int read_pid_max(void)
>  {
> -       pid_t pidmax;
> +       unsigned long result;
> +       char *end, buf[32];
> +       FILE *fp;
> +
> +       fp = fopen("/proc/sys/kernel/pid_max", "r");
> +       if (!fp) {
> +               perror("fopen");
> +               return -1;
> +       }
> +
> +       if (!fgets(buf, sizeof(buf), fp))
> +               return -1;
> +
> +       result = strtoul(buf, &end, 10);
> +       if (end == buf)
> +               return -1;
> +
> +       pidmax = result;
> +
> +       return 0;
> +}
>
> -// FIXME: Read this from /proc/sys/kernel/pid_max on startup
> +void pids_init(void)
> +{
> +       if (read_pid_max()) {
>  #ifdef __x86_64__
> -       pidmax = 4194304;
> +               pidmax = 4194304;
>  #else
> -       pidmax = 32768;
> +               pidmax = 32768;
>  #endif
> +               printf("Couldn't read pid_max from proc\n");
> +       }
>
> +       printf("Using pid_max = %d\n", pidmax);
> +}
> +
> +int pid_is_valid(pid_t pid)
> +{
>         if ((pid > pidmax) || (pid < 1)) {
>                 output(0, "Sanity check failed! Found pid %d!\n", pid);
>                 return FALSE;
> diff --git a/trinity.c b/trinity.c
> index b95d287..0b88150 100644
> --- a/trinity.c
> +++ b/trinity.c
> @@ -212,6 +212,8 @@ int main(int argc, char* argv[])
>
>         parse_devices();
>
> +       pids_init();
> +
>         setup_main_signals();
>
>         if (check_tainted() != 0) {
> --
> 1.7.10.4
>
> --
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