package/hotplug2/patches/120-throttling.patch

   1 --- a/hotplug2.c
   2 +++ b/hotplug2.c
   3 @@ -21,6 +21,7 @@
   4  #include <sys/mman.h>
   5  #include <linux/types.h>
   6  #include <linux/netlink.h>
   7 +#include <poll.h>
   8
   9  #include "mem_utils.h"
  10  #include "filemap_utils.h"
  11 @@ -492,6 +493,11 @@
  12         char *coldplug_command = NULL;
  13         char *rules_file = HOTPLUG2_RULE_PATH;
  14         sigset_t block_mask;
  15 +       struct pollfd msg_poll;
  16 +
  17 +       struct hotplug2_event_t *backlog = NULL;
  18 +       struct hotplug2_event_t *backlog_tail = NULL;
  19 +       int n_backlog = 0;
  20
  21         struct rules_t *rules = NULL;
  22         struct filemap_t filemap;
  23 @@ -602,6 +608,8 @@
  24          * Open netlink socket to read the uevents
  25          */
  26         netlink_socket = init_netlink_socket(NETLINK_BIND);
  27 +       msg_poll.fd = netlink_socket;
  28 +       msg_poll.events = POLLIN;
  29
  30         if (netlink_socket == -1) {
  31                 ERROR("netlink init","Unable to open netlink socket.");
  32 @@ -642,20 +650,45 @@
  33          * Main loop reading uevents
  34          */
  35         while (!terminate) {
  36 -               /*
  37 -                * Read the uevent packet
  38 -                */
  39 -               size = recv(netlink_socket, &buffer, sizeof(buffer), 0);
  40 -               recv_errno = errno;
  41 +               if ((n_backlog > 0) && (child_c < max_child_c)) {
  42 +                       /* dequeue backlog message */
  43 +                       tmpevent = backlog;
  44 +                       backlog = backlog->next;
  45 +                       n_backlog--;
  46 +                       if (backlog_tail == tmpevent)
  47 +                               backlog_tail = NULL;
  48 +               } else {
  49 +                       /*
  50 +                        * Read the uevent packet
  51 +                        */
  52 +                       if (n_backlog >= HOTPLUG2_MSG_BACKLOG) {
  53 +                               usleep(HOTPLUG2_THROTTLE_INTERVAL * 1000);
  54 +                               continue;
  55 +                       }
  56 +
  57 +                       if ((n_backlog > 0) && (child_c >= max_child_c)) {
  58 +                               int fds;
  59 +                               msg_poll.revents = 0;
  60 +                               fds = poll(&msg_poll, 1, HOTPLUG2_THROTTLE_INTERVAL);
  61 +                               if (fds < 0) {
  62 +                                       perror("POLL FAILED");
  63 +                                       continue;
  64 +                               }
  65 +                               if (fds == 0)
  66 +                                       continue;
  67 +                       }
  68 +                       size = recv(netlink_socket, &buffer, sizeof(buffer), 0);
  69 +                       recv_errno = errno;
  70
  71 -               /*
  72 -                * Parse the event into an event structure
  73 -                */
  74 -               tmpevent = get_hotplug2_event(buffer, size);
  75 +                       /*
  76 +                        * Parse the event into an event structure
  77 +                        */
  78 +                       tmpevent = get_hotplug2_event(buffer, size);
  79
  80 -               if (tmpevent == NULL) {
  81 -                       ERROR("reading events", "Malformed event read (missing action prefix).");
  82 -                       continue;
  83 +                       if (tmpevent == NULL) {
  84 +                               ERROR("reading events", "Malformed event read (missing action prefix).");
  85 +                               continue;
  86 +                       }
  87                 }
  88
  89                 /*
  90 @@ -706,13 +739,16 @@
  91                          * Unless, of course, we've specified otherwise and no rules that match
  92                          * need throttling.
  93                          */
  94 -                       if (!flags & FLAG_NOTHROTTLE) {
  95 -                               /*
  96 -                                * Okay, throttle away!
  97 -                                */
  98 -                               while (child_c >= max_child_c) {
  99 -                                       usleep(HOTPLUG2_THROTTLE_INTERVAL);
 100 -                               }
 101 +                       if (!(flags & FLAG_NOTHROTTLE) && (child_c >= max_child_c)) {
 102 +                               /* log the packet and process it later */
 103 +                               if (backlog_tail)
 104 +                                       backlog_tail->next = tmpevent;
 105 +                               else
 106 +                                       backlog = tmpevent;
 107 +                               tmpevent->next = NULL;
 108 +                               backlog_tail = tmpevent;
 109 +                               n_backlog++;
 110 +                               continue;
 111                         }
 112
 113                         sigemptyset(&block_mask);
 114 --- a/hotplug2.h
 115 +++ b/hotplug2.h
 116 @@ -45,9 +45,9 @@
 117  #define DBG(action, fmt, arg...)
 118  #endif
 119
 120 +#define HOTPLUG2_MSG_BACKLOG   64
 121  #define UEVENT_BUFFER_SIZE             2048
 122 -#define HOTPLUG2_POLL_INTERVAL         20000
 123 -#define HOTPLUG2_THROTTLE_INTERVAL     10000
 124 +#define HOTPLUG2_THROTTLE_INTERVAL     50
 125  #define HOTPLUG2_RULE_PATH             "/etc/hotplug2.rules"
 126
 127  #define ACTION_ADD                     0
 128 @@ -76,6 +76,7 @@
 129         int env_vars_c;
 130         char *plain;
 131         int plain_s;
 132 +       struct hotplug2_event_t *next;
 133  };
 134
 135  struct options_t {