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libbb: move netlink socket binding to the utility function

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function                                             old     new   delta
create_and_bind_to_netlink                             -     134    +134
ifplugd_main                                        1117    1052     -65
uevent_main                                          399     306     -93
mdev_main                                            314     215     -99
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/3 up/down: 134/-257)         Total: -123 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2019-06-03 14:16:52 +02:00
parent 498cec202a
commit 45e3967c20
5 changed files with 55 additions and 56 deletions
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28
util-linux/mdev.c
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@ -1225,28 +1225,16 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
/*
* Daemon mode listening on uevent netlink socket.
*/
struct sockaddr_nl sa;
int fd;
//TODO: reuse same code in uevent
// Subscribe for UEVENT kernel messages
sa.nl_family = AF_NETLINK;
sa.nl_pad = 0;
sa.nl_pid = getpid();
sa.nl_groups = 1 << 0;
fd = xsocket(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
xbind(fd, (struct sockaddr *) &sa, sizeof(sa));
close_on_exec_on(fd);
// Without a sufficiently big RCVBUF, a ton of simultaneous events
// can trigger ENOBUFS on read, which is unrecoverable.
// Reproducer:
// mdev -d
// find /sys -name uevent -exec sh -c 'echo add >"{}"' ';'
//
// SO_RCVBUFFORCE (root only) can go above net.core.rmem_max sysctl
setsockopt_SOL_SOCKET_int(fd, SO_RCVBUF, RCVBUF);
setsockopt_SOL_SOCKET_int(fd, SO_RCVBUFFORCE, RCVBUF);
/* Subscribe for UEVENT kernel messages */
/* Without a sufficiently big RCVBUF, a ton of simultaneous events
* can trigger ENOBUFS on read, which is unrecoverable.
* Reproducer:
* mdev -d
* find /sys -name uevent -exec sh -c 'echo add >"{}"' ';'
*/
fd = create_and_bind_to_netlink(NETLINK_KOBJECT_UEVENT, 1 << 0, RCVBUF);
/*
* Make inital scan after the uevent socket is alive and