git: 2e72208b6c62 - main - ip_mroute: do not call epoch_waitwhen lock is taken

The branch main has been updated by wma:

URL: https://cgit.FreeBSD.org/src/commit/?id=2e72208b6c622505323ed48dc58830fc307392b1

commit 2e72208b6c622505323ed48dc58830fc307392b1
Author:     Wojciech Macek <wma@FreeBSD.org>
AuthorDate: 2022-01-11 10:08:35 +0000
Commit:     Wojciech Macek <wma@FreeBSD.org>
CommitDate: 2022-01-11 10:19:32 +0000

    ip_mroute: do not call epoch_waitwhen lock is taken
    
    mrouter_done is called with RAW IP lock taken. Some annoying
    printfs are visible on the console if INVARIANTS option is enabled.
    
    Provide atomic-based mechanism which counts enters and exits from/to
    critical section in ip_input and ip_output.
    Before de-initialization of function pointers ensure (with busy-wait)
    that mrouter de-initialization is visible to all readers and that we don't
    remove pointers (like ip_mforward etc.) in the middle of packet processing.
---
 sys/netinet/ip_mroute.h | 9 +++++----
 sys/netinet/raw_ip.c    | 1 +
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/sys/netinet/ip_mroute.h b/sys/netinet/ip_mroute.h
index 65c5bdd3a025..faf5b8c72a46 100644
--- a/sys/netinet/ip_mroute.h
+++ b/sys/netinet/ip_mroute.h
@@ -365,11 +365,12 @@ extern int	(*ip_mrouter_set)(struct socket *, struct sockopt *);
 extern int	(*ip_mrouter_get)(struct socket *, struct sockopt *);
 extern int	(*ip_mrouter_done)(void);
 extern int	(*mrt_ioctl)(u_long, caddr_t, int);
+extern int	ip_mrouter_critical_section_cnt;
 
-#define	MROUTER_RLOCK_TRACKER	struct epoch_tracker mrouter_et
-#define	MROUTER_RLOCK()	epoch_enter_preempt(net_epoch_preempt, &mrouter_et)
-#define	MROUTER_RUNLOCK()	epoch_exit_preempt(net_epoch_preempt, &mrouter_et)
-#define	MROUTER_WAIT()	epoch_wait_preempt(net_epoch_preempt)
+#define	MROUTER_RLOCK_TRACKER
+#define	MROUTER_RLOCK()		atomic_add_int(&ip_mrouter_critical_section_cnt, 1)
+#define	MROUTER_RUNLOCK()	atomic_subtract_int(&ip_mrouter_critical_section_cnt, 1)
+#define	MROUTER_WAIT()		do {} while (atomic_load_int(&ip_mrouter_critical_section_cnt) != 0)
 
 #endif /* _KERNEL */
 
diff --git a/sys/netinet/raw_ip.c b/sys/netinet/raw_ip.c
index 7c495745806e..dc49c36f25ad 100644
--- a/sys/netinet/raw_ip.c
+++ b/sys/netinet/raw_ip.c
@@ -120,6 +120,7 @@ VNET_DEFINE(struct socket *, ip_mrouter);
 int (*ip_mrouter_set)(struct socket *, struct sockopt *);
 int (*ip_mrouter_get)(struct socket *, struct sockopt *);
 int (*ip_mrouter_done)(void);
+int ip_mrouter_critical_section_cnt;
 int (*ip_mforward)(struct ip *, struct ifnet *, struct mbuf *,
 		   struct ip_moptions *);
 int (*mrt_ioctl)(u_long, caddr_t, int);