From 00a12a9d167ca8d7771f3f957e85c6cdc580a43f Mon Sep 17 00:00:00 2001 From: Ian Jackson Date: Wed, 25 Jul 2012 17:39:17 +0100 Subject: [PATCH] libxl: fix transaction leak in logdirty error path libxl__domain_suspend_common_switch_qemu_logdirty would leak t if there was an error. Fix this. Also, document the intended usage for libxl__xs_transaction_* in the doc comment in libxl_internal.h. Reported-by: Ian Campbell Signed-off-by: Ian Jackson Acked-by: Ian Campbell Committed-by: Ian Campbell --- tools/libxl/libxl_dom.c | 1 + tools/libxl/libxl_internal.h | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+) diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c index cecda9ba84..bd4c9b448d 100644 --- a/tools/libxl/libxl_dom.c +++ b/tools/libxl/libxl_dom.c @@ -628,6 +628,7 @@ void libxl__domain_suspend_common_switch_qemu_logdirty out: LOG(ERROR,"logdirty switch failed (rc=%d), aborting suspend",rc); + libxl__xs_transaction_abort(gc, &t); switch_logdirty_done(egc,dss,-1); } diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index f832fbd9e5..728d6c0af2 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -550,6 +550,42 @@ int libxl__xs_rm_checked(libxl__gc *gc, xs_transaction_t t, const char *path); * +1 commit conflict; transaction has been destroyed and caller * must go round again (call _start again and retry) * 0 committed successfully + * + * The intended usage pattern looks like this: + * int some_function() + * { + * int rc; + * xs_transaction_t t = 0; + * // other initialisations + * + * // do whatever you need to do before the xenstore stuff + * // errors? set rc and goto out. + * + * for (;;) { + * rc = libxl__xs_transaction_start(gc, &t); + * if (rc) goto out; + * + * // do your work here, including all xenstore reads and writes + * // libxl__xs_*_checked are useful; pass them t. + * // errors? set rc and goto out. + * + * rc = libxl__xs_transaction_commit(gc, &t); + * if (!rc) break; + * if (rc<0) goto out; + * } + * + * // now the xenstore transaction succeeded + * // do whatever else you need to do + * // errors? set rc and goto out. + * + * return something; + * + * out: + * // other cleanups + * libxl__xs_transaction_abort(gc, &t); + * // other cleanups + * return rc; + * } */ int libxl__xs_transaction_start(libxl__gc *gc, xs_transaction_t *t); int libxl__xs_transaction_commit(libxl__gc *gc, xs_transaction_t *t); -- 2.39.5