From bff439345cafa59a4bd72c2a20591e7bd8441b47 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Fri, 2 May 2025 17:04:50 +0000
Subject:  Increase default kbufsz to 1 MiB; don't die on ENOBUFS (but spam)

Signed-off-by: Laurent Bercot <ska@appnovation.com>
---
 src/mdevd/mdevd-coldplug.c    |  4 ++--
 src/mdevd/mdevd.c             |  2 +-
 src/mdevd/mdevd_uevent_read.c | 13 +++++++++----
 3 files changed, 12 insertions(+), 7 deletions(-)

(limited to 'src')

diff --git a/src/mdevd/mdevd-coldplug.c b/src/mdevd/mdevd-coldplug.c
index 6b8953f..1dd0982 100644
--- a/src/mdevd/mdevd-coldplug.c
+++ b/src/mdevd/mdevd-coldplug.c
@@ -15,7 +15,7 @@
 
 #include "mdevd-internal.h"
 
-#define USAGE "mdevd-coldplug [ -v verbosity ] [ -s slashsys ] [ -O nlgroup ] [ -b kbufsize ]"
+#define USAGE "mdevd-coldplug [ -v verbosity ] [ -s slashsys ] [ -O nlgroup ] [ -b kbufsz ]"
 #define dieusage() strerr_dieusage(100, USAGE)
 
 static char subsystem[PATH_MAX] = "" ;
@@ -95,7 +95,7 @@ int main (int argc, char const *const *argv, char const *const *envp)
   char const *slashsys = "/sys" ;
   unsigned int verbosity = 1 ;
   unsigned int nlgroup = 0 ;
-  unsigned int kbufsz = 512288 ;
+  unsigned int kbufsz = 1048576 ;
   int nlfd = -1 ;
   PROG = "mdevd-coldplug" ;
   {
diff --git a/src/mdevd/mdevd.c b/src/mdevd/mdevd.c
index 6b82874..f5222f7 100644
--- a/src/mdevd/mdevd.c
+++ b/src/mdevd/mdevd.c
@@ -904,7 +904,7 @@ int main (int argc, char const *const *argv)
   char const *configfile = "/etc/mdev.conf" ;
   iopause_fd x[2] = { { .events = IOPAUSE_READ }, { .events = IOPAUSE_READ } } ;
   unsigned int notif = 0 ;
-  unsigned int kbufsz = 512288 ;
+  unsigned int kbufsz = 1048576 ;
   char const *slashdev = "/dev" ;
   int docoldplug = 0 ;
   unsigned int intake = 1 ;
diff --git a/src/mdevd/mdevd_uevent_read.c b/src/mdevd/mdevd_uevent_read.c
index 1c84f2d..38be5ea 100644
--- a/src/mdevd/mdevd_uevent_read.c
+++ b/src/mdevd/mdevd_uevent_read.c
@@ -38,10 +38,15 @@ static inline size_t netlink_read (int fd, char *s, uint32_t options, unsigned i
     .msg_controllen = 0,
     .msg_flags = 0
   } ;
-  ssize_t r = sanitize_read(fd_recvmsg(fd, &msg)) ;
-  if (r < 0)
-    strerr_diefu1sys(111, "receive netlink message") ;
-  if (!r) return 0 ;
+  ssize_t r ;
+  for (;;)
+  {
+    r = sanitize_read(fd_recvmsg(fd, &msg)) ;
+    if (r > 0) break ;
+    if (!r) return 0 ;
+    if (errno != ENOBUFS) strerr_diefu1sys(111, "read netlink message") ;
+    strerr_warnw1x("missed events! you should increase the -b kbufsz value") ;
+  }
   if (msg.msg_flags & MSG_TRUNC)
     strerr_diefu1x(111, "buffer too small for netlink message") ;
   if (options & 1 && nl.nl_pid)
-- 
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