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From: Richard Scheffenegger <rscheff@FreeBSD.org>
Subject: git: f1650b162d26 - stable/13 - Make sbuf_drain safe for external use
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The branch stable/13 has been updated by rscheff:
URL: https://cgit.FreeBSD.org/src/commit/?id=f1650b162d26b91b6b170f10250f46617a0bcedc
commit f1650b162d26b91b6b170f10250f46617a0bcedc
Author: Richard Scheffenegger <rscheff@FreeBSD.org>
AuthorDate: 2021-04-02 18:11:45 +0000
Commit: Richard Scheffenegger <rscheff@FreeBSD.org>
CommitDate: 2021-04-16 18:51:20 +0000
Make sbuf_drain safe for external use
While sbuf_drain was an internal function, two
KASSERTS checked the sanity of it being called.
However, an external caller may be ignorant if
there is any data to drain, or if an error has
already accumulated. Be nice and return immediately
with the accumulated error.
MFC after: 2 weeks
Reviewed By: tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D29544
(cherry picked from commit cad4fd0365a5e3235e715e072e6ee9dffaa7a3ab)
---
sys/kern/subr_sbuf.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/sys/kern/subr_sbuf.c b/sys/kern/subr_sbuf.c
index 66822115dbcb..cdeaf690208f 100644
--- a/sys/kern/subr_sbuf.c
+++ b/sys/kern/subr_sbuf.c
@@ -388,8 +388,12 @@ sbuf_drain(struct sbuf *s)
{
int len;
- KASSERT(s->s_len > 0, ("Shouldn't drain empty sbuf %p", s));
- KASSERT(s->s_error == 0, ("Called %s with error on %p", __func__, s));
+ /*
+ * Immediately return when no work to do,
+ * or an error has already been accumulated.
+ */
+ if ((s->s_len == 0) || (s->s_error != 0))
+ return(s->s_error);
if (SBUF_DODRAINTOEOR(s) && s->s_rec_off == 0)
return (s->s_error = EDEADLK);