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uevent: increase netlink buffer sizes

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2020-11-22 13:34:07 +01:00
parent 3cd55d49a2
commit a569fd37fe
1 changed files with 14 additions and 10 deletions
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24
util-linux/uevent.c
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@ -26,8 +26,6 @@
#include "common_bufsiz.h" #include "common_bufsiz.h"
#include <linux/netlink.h> #include <linux/netlink.h>
#define BUFFER_SIZE 16*1024
#define env ((char **)bb_common_bufsiz1) #define env ((char **)bb_common_bufsiz1)
#define INIT_G() do { setup_common_bufsiz(); } while (0) #define INIT_G() do { setup_common_bufsiz(); } while (0)
enum { enum {
@ -37,10 +35,16 @@ enum {
*/ */
}; };
#ifndef SO_RCVBUFFORCE enum {
#define SO_RCVBUFFORCE 33 /* socket receive buffer of 2MiB proved to be too small:
#endif * http://lists.busybox.net/pipermail/busybox/2019-December/087665.html
enum { RCVBUF = 2 * 1024 * 1024 }; * 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, char **argv) MAIN_EXTERNALLY_VISIBLE;
int uevent_main(int argc UNUSED_PARAM, char **argv) int uevent_main(int argc UNUSED_PARAM, char **argv)
@ -57,7 +61,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv)
// Reproducer: // Reproducer:
// uevent mdev & // uevent mdev &
// find /sys -name uevent -exec sh -c 'echo add >"{}"' ';' // 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 (;;) { for (;;) {
char *netbuf; char *netbuf;
@ -69,7 +73,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv)
// for a new uevent notification to come in. // for a new uevent notification to come in.
// We use a fresh mmap so that buffer is not allocated // We use a fresh mmap so that buffer is not allocated
// until kernel actually starts filling it. // until kernel actually starts filling it.
netbuf = mmap(NULL, BUFFER_SIZE, netbuf = mmap(NULL, USER_RCVBUF,
PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON, MAP_PRIVATE | MAP_ANON,
/* ignored: */ -1, 0); /* ignored: */ -1, 0);
@ -77,7 +81,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv)
bb_simple_perror_msg_and_die("mmap"); bb_simple_perror_msg_and_die("mmap");
// Here we block, possibly for a very long time // 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) if (len < 0)
bb_simple_perror_msg_and_die("read"); bb_simple_perror_msg_and_die("read");
end = netbuf + len; end = netbuf + len;
@ -108,7 +112,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv)
while (env[idx]) while (env[idx])
bb_unsetenv(env[idx++]); bb_unsetenv(env[idx++]);
} }
munmap(netbuf, BUFFER_SIZE); munmap(netbuf, USER_RCVBUF);
} }
return 0; // not reached return 0; // not reached