git: dc5281a7d439 - stable/12 - Export sbuf_drain to orchestrate lock and drain action

[Richard Scheffenegger]

The branch stable/12 has been updated by rscheff:

URL: https://cgit.FreeBSD.org/src/commit/?id=dc5281a7d43917c55905d8b83a5bef69b8013071

commit dc5281a7d43917c55905d8b83a5bef69b8013071
Author:     Richard Scheffenegger <rscheff at FreeBSD.org>
AuthorDate: 2021-03-31 16:25:53 +0000
Commit:     Richard Scheffenegger <rscheff at FreeBSD.org>
CommitDate: 2021-04-16 19:27:15 +0000

    Export sbuf_drain to orchestrate lock and drain action
    
    While exporting large amounts of data to a sysctl
    request, datastructures may need to be locked.
    
    Exporting the sbuf_drain function allows the
    coordination between drain events and held
    locks, to avoid stalls.
    
    PR:             254333
    Reviewed By:    jhb
    MFC after:      2 weeks
    Sponsored by:   NetApp, Inc.
    Differential Revision: https://reviews.freebsd.org/D29481
    
    (cherry picked from commit c804c8f2c58ba42d476de07fbceff9ac4dd95f0e)
---
 sys/kern/subr_sbuf.c | 2 +-
 sys/sys/sbuf.h       | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/sys/kern/subr_sbuf.c b/sys/kern/subr_sbuf.c
index 8fba9710debc..c8f2af2ebca2 100644
--- a/sys/kern/subr_sbuf.c
+++ b/sys/kern/subr_sbuf.c
@@ -375,7 +375,7 @@ sbuf_set_drain(struct sbuf *s, sbuf_drain_func *func, void *ctx)
 /*
  * Call the drain and process the return.
  */
-static int
+int
 sbuf_drain(struct sbuf *s)
 {
 	int len;
diff --git a/sys/sys/sbuf.h b/sys/sys/sbuf.h
index a3b0a179c268..1927996c8f38 100644
--- a/sys/sys/sbuf.h
+++ b/sys/sys/sbuf.h
@@ -92,6 +92,7 @@ int		 sbuf_vprintf(struct sbuf *, const char *, __va_list)
 	__printflike(2, 0);
 int		 sbuf_putc(struct sbuf *, int);
 void		 sbuf_set_drain(struct sbuf *, sbuf_drain_func *, void *);
+int		 sbuf_drain(struct sbuf *);
 int		 sbuf_trim(struct sbuf *);
 int		 sbuf_error(const struct sbuf *);
 int		 sbuf_finish(struct sbuf *);