[PATCH v2 12/17] tools/ocaml/libs/mmap: mark mmap/munmap as blocking

From: "Edwin Török" <edvin.torok@citrix.com>
To: <xen-devel@lists.xenproject.org>
Cc: "Edwin Török" <edvin.torok@citrix.com>,
	"Christian Lindig" <christian.lindig@citrix.com>,
	"David Scott" <dave@recoil.org>,
	"Ian Jackson" <iwj@xenproject.org>, "Wei Liu" <wl@xen.org>
Subject: [PATCH v2 12/17] tools/ocaml/libs/mmap: mark mmap/munmap as blocking
Date: Tue, 11 May 2021 19:05:25 +0100	[thread overview]
Message-ID: <294a60be29027d33b0a1d154b7d576237c7dd420.1620755942.git.edvin.torok@citrix.com> (raw)
In-Reply-To: <cover.1620755942.git.edvin.torok@citrix.com>

These functions can potentially take some time,
so allow other OCaml code to proceed meanwhile (if any).

Signed-off-by: Edwin Török <edvin.torok@citrix.com>
---
 tools/ocaml/libs/mmap/xenmmap_stubs.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/ocaml/libs/mmap/xenmmap_stubs.c b/tools/ocaml/libs/mmap/xenmmap_stubs.c
index d7a97c76f5..e8d2d6add5 100644
--- a/tools/ocaml/libs/mmap/xenmmap_stubs.c
+++ b/tools/ocaml/libs/mmap/xenmmap_stubs.c
@@ -28,6 +28,7 @@
 #include <caml/fail.h>
 #include <caml/callback.h>
 #include <caml/unixsupport.h>
+#include <caml/signals.h>
 
 #define Wsize_bsize_round(n) (Wsize_bsize( (n) + sizeof(value) - 1 ))
 
@@ -69,7 +70,9 @@ CAMLprim value stub_mmap_init(value fd, value pflag, value mflag,
 		caml_invalid_argument("negative offset");
 	length = Int_val(len);
 
+	caml_enter_blocking_section();
 	addr = mmap(NULL, length, c_pflag, c_mflag, Int_val(fd), Int_val(offset));
+	caml_leave_blocking_section();
 	if (MAP_FAILED == addr)
 		uerror("mmap", Nothing);
 
@@ -80,10 +83,15 @@ CAMLprim value stub_mmap_init(value fd, value pflag, value mflag,
 CAMLprim value stub_mmap_final(value intf)
 {
 	CAMLparam1(intf);
+	struct mmap_interface interface = *Intf_val(intf);
 
-	if (Intf_val(intf)->addr != MAP_FAILED)
-		munmap(Intf_val(intf)->addr, Intf_val(intf)->len);
+	/* mark it as freed, in case munmap below fails, so we don't retry it */
 	Intf_val(intf)->addr = MAP_FAILED;
+	if (interface.addr != MAP_FAILED) {
+		caml_enter_blocking_section();
+		munmap(interface.addr, interface.len);
+		caml_leave_blocking_section();
+	}
 
 	CAMLreturn(Val_unit);
 }
-- 
2.25.1


