a569fd37f
Denys Vlasenko
2020-11-22
Subject
uevent: increase netlink buffer sizes
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util-linux/uevent.c+14 -10
| @@ -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 | |