diff options
| -rw-r--r-- | util-linux/uevent.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/util-linux/uevent.c b/util-linux/uevent.c index 57d9328..2f1135f 100644 --- a/util-linux/uevent.c +++ b/util-linux/uevent.c @@ -26,8 +26,6 @@ #include "common_bufsiz.h" #include <linux/netlink.h> -#define BUFFER_SIZE 16*1024 - #define env ((char **)bb_common_bufsiz1) #define INIT_G() do { setup_common_bufsiz(); } while (0) enum { @@ -37,10 +35,16 @@ enum { */ }; -#ifndef SO_RCVBUFFORCE -#define SO_RCVBUFFORCE 33 -#endif -enum { RCVBUF = 2 * 1024 * 1024 }; +enum { + /* socket receive buffer of 2MiB proved to be too small: + * http://lists.busybox.net/pipermail/busybox/2019-December/087665.html + * Udevd seems to use a whooping 128MiB. + * The socket receive buffer size is just a resource limit. + * The buffers are allocated lazily so the memory is not wasted. + */ + KERN_RCVBUF = 128 * 1024 * 1024, + USER_RCVBUF = 16 * 1024, +}; int uevent_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int uevent_main(int argc UNUSED_PARAM, char **argv) @@ -57,7 +61,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv) // Reproducer: // uevent mdev & // find /sys -name uevent -exec sh -c 'echo add >"{}"' ';' - fd = create_and_bind_to_netlink(NETLINK_KOBJECT_UEVENT, /*groups:*/ 1 << 0, RCVBUF); + fd = create_and_bind_to_netlink(NETLINK_KOBJECT_UEVENT, /*groups:*/ 1 << 0, KERN_RCVBUF); for (;;) { char *netbuf; @@ -69,7 +73,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv) // for a new uevent notification to come in. // We use a fresh mmap so that buffer is not allocated // until kernel actually starts filling it. - netbuf = mmap(NULL, BUFFER_SIZE, + netbuf = mmap(NULL, USER_RCVBUF, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, /* ignored: */ -1, 0); @@ -77,7 +81,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv) bb_simple_perror_msg_and_die("mmap"); // Here we block, possibly for a very long time - len = safe_read(fd, netbuf, BUFFER_SIZE - 1); + len = safe_read(fd, netbuf, USER_RCVBUF - 1); if (len < 0) bb_simple_perror_msg_and_die("read"); end = netbuf + len; @@ -108,7 +112,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv) while (env[idx]) bb_unsetenv(env[idx++]); } - munmap(netbuf, BUFFER_SIZE); + munmap(netbuf, USER_RCVBUF); } return 0; // not reached |