Date: Thu, 9 May 2024 11:05:37 GMT
From: Roger Pau =?utf-8?Q?Monn=C3=A9?= <royger@FreeBSD.org>
To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org
Subject: git: ee72bc1d1ff8 - main - xen/debug: remove usage of sbuf_{clear,finish}() on drained sbuf
Message-ID: <202405091105.449B5bm9013006@gitrepo.freebsd.org>
next in thread | raw e-mail | index | archive | help
The branch main has been updated by royger: URL: https://cgit.FreeBSD.org/src/commit/?id=ee72bc1d1ff8aa8704d5861a10ea3514154ff74d commit ee72bc1d1ff8aa8704d5861a10ea3514154ff74d Author: Roger Pau Monné <royger@FreeBSD.org> AuthorDate: 2024-05-02 13:12:16 +0000 Commit: Roger Pau Monné <royger@FreeBSD.org> CommitDate: 2024-05-09 10:50:08 +0000 xen/debug: remove usage of sbuf_{clear,finish}() on drained sbuf Using sbuf_clear() on a drained sbuf is explicitly prohibited, and using sbuf_finish() after printing a trace leads to a single trace being printed, as after calling sbuf_finish() further attempts to use the same sbuf will lead to a panic. While there also switch to using xen_emergency_print() instead of attempting to write directly to the hypervisor console. xen_emergency_print() can be implemented per-arch to use a different mechanism than the console hypercall (note the default implementation still uses the console hypercall). Fixes: df62b8a25f47 ('xen: add a handler for the debug interrupt') Sponsored by: Cloud Software Group Reviewed by: markj Differential review: https://reviews.freebsd.org/D45060 --- sys/dev/xen/debug/debug.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/sys/dev/xen/debug/debug.c b/sys/dev/xen/debug/debug.c index f17d0c612262..2889b5efdba7 100644 --- a/sys/dev/xen/debug/debug.c +++ b/sys/dev/xen/debug/debug.c @@ -58,8 +58,11 @@ static struct sbuf *buf; static int xendebug_drain(void *arg, const char *str, int len) { - - HYPERVISOR_console_write(__DECONST(char *, str), len); + /* + * Use xen_emergency_print() instead of xc_printf() to avoid the + * overhead of parsing a format string when it's not needed. + */ + xen_emergency_print(str, len); return (len); } @@ -75,10 +78,9 @@ xendebug_filter(void *arg __unused) stack_save(&st); mtx_lock_spin(&lock); - sbuf_clear(buf); xc_printf("Printing stack trace vCPU%u\n", XEN_VCPUID()); stack_sbuf_print_ddb(buf, &st); - sbuf_finish(buf); + sbuf_drain(buf); mtx_unlock_spin(&lock); #endif
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202405091105.449B5bm9013006>