From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Sat, 26 Aug 2017 22:54:24 +0000 (+0200)
Subject: userfaultfd: streamline logic
X-Git-Tag: v4.19~47
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d4555fd56e3837a9afdd1eb907c03e68ca4b0015;p=strace

userfaultfd: streamline logic

Make userfaultfd ioctl handling more in line with other ioctl decoders.

* userfaultfd.c (uffdio_ioctl): Return RVAL_DECODED | 1, break instead
of returning in specific command handlers, return 0 on entering paths,
move exiting paths out of else branch of entering(tcp) condition.
---

diff --git a/userfaultfd.c b/userfaultfd.c
index 965bd330..150d98fb 100644
--- a/userfaultfd.c
+++ b/userfaultfd.c
@@ -72,10 +72,11 @@ uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
 	case UFFDIO_API: {
 		uint64_t *entering_features;
 		struct uffdio_api ua;
+
 		if (entering(tcp)) {
 			tprints(", ");
 			if (umove_or_printaddr(tcp, arg, &ua))
-				return RVAL_DECODED | 1;
+				break;
 			PRINT_FIELD_X("{", ua, api);
 			PRINT_FIELD_FLAGS(", ", ua, features, uffd_api_features,
 					  "UFFD_FEATURE_???");
@@ -84,26 +85,32 @@ uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
 				*entering_features = ua.features;
 				set_tcb_priv_data(tcp, entering_features, free);
 			}
-		} else {
-			if (!syserror(tcp) && !umove(tcp, arg, &ua)) {
-				entering_features = get_tcb_priv_data(tcp);
-				if (!entering_features
-				    || *entering_features != ua.features) {
-					PRINT_FIELD_FLAGS(" => ", ua, features,
-							  uffd_api_features,
-							  "UFFD_FEATURE_???");
-				}
-				PRINT_FIELD_FLAGS(", ", ua, ioctls,
-						  uffd_api_flags,
-						  "_UFFDIO_???");
+
+			return 0;
+		}
+
+		if (!syserror(tcp) && !umove(tcp, arg, &ua)) {
+			entering_features = get_tcb_priv_data(tcp);
+
+			if (!entering_features
+			    || *entering_features != ua.features) {
+				PRINT_FIELD_FLAGS(" => ", ua, features,
+						  uffd_api_features,
+						  "UFFD_FEATURE_???");
 			}
-			tprints("}");
+
+			PRINT_FIELD_FLAGS(", ", ua, ioctls, uffd_api_flags,
+					  "_UFFDIO_???");
 		}
-		return 1;
+
+		tprints("}");
+
+		break;
 	}
 
 	case UFFDIO_COPY: {
 		struct uffdio_copy uc;
+
 		if (entering(tcp)) {
 			tprints(", ");
 			if (umove_or_printaddr(tcp, arg, &uc))
@@ -113,16 +120,21 @@ uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
 			PRINT_FIELD_X(", ", uc, len);
 			PRINT_FIELD_FLAGS(", ", uc, mode, uffd_copy_flags,
 					  "UFFDIO_COPY_???");
-		} else {
-			if (!syserror(tcp) && !umove(tcp, arg, &uc))
-				PRINT_FIELD_X(", ", uc, copy);
-			tprints("}");
+
+			return 0;
 		}
-		return 1;
+
+		if (!syserror(tcp) && !umove(tcp, arg, &uc))
+			PRINT_FIELD_X(", ", uc, copy);
+
+		tprints("}");
+
+		break;
 	}
 
 	case UFFDIO_REGISTER: {
 		struct uffdio_register ur;
+
 		if (entering(tcp)) {
 			tprints(", ");
 			if (umove_or_printaddr(tcp, arg, &ur))
@@ -131,28 +143,36 @@ uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
 			PRINT_FIELD_FLAGS(", ", ur, mode,
 					  uffd_register_mode_flags,
 					  "UFFDIO_REGISTER_MODE_???");
-		} else {
-			if (!syserror(tcp) && !umove(tcp, arg, &ur)) {
-				PRINT_FIELD_FLAGS(", ", ur, ioctls,
-						  uffd_register_ioctl_flags,
-						  "UFFDIO_???");
-			}
-			tprints("}");
+
+			return 0;
+		}
+
+		if (!syserror(tcp) && !umove(tcp, arg, &ur)) {
+			PRINT_FIELD_FLAGS(", ", ur, ioctls,
+					  uffd_register_ioctl_flags,
+					  "UFFDIO_???");
 		}
-		return 1;
+
+		tprints("}");
+
+		break;
 	}
 
 	case UFFDIO_UNREGISTER:
 	case UFFDIO_WAKE: {
 		struct uffdio_range ura;
+
 		tprints(", ");
+
 		if (!umove_or_printaddr(tcp, arg, &ura))
 			tprintf_uffdio_range(&ura);
-		return RVAL_DECODED | 1;
+
+		break;
 	}
 
 	case UFFDIO_ZEROPAGE: {
 		struct uffdio_zeropage uz;
+
 		if (entering(tcp)) {
 			tprints(", ");
 			if (umove_or_printaddr(tcp, arg, &uz))
@@ -160,16 +180,22 @@ uffdio_ioctl(struct tcb *const tcp, const unsigned int code,
 			PRINT_FIELD_UFFDIO_RANGE("{", uz, range);
 			PRINT_FIELD_FLAGS(", ", uz, mode, uffd_zeropage_flags,
 					  "UFFDIO_ZEROPAGE_???");
-		} else {
-			if (!syserror(tcp) && !umove(tcp, arg, &uz))
-				PRINT_FIELD_X(", ", uz, zeropage);
-			tprints("}");
+
+			return 0;
 		}
-		return 1;
+
+		if (!syserror(tcp) && !umove(tcp, arg, &uz))
+			PRINT_FIELD_X(", ", uz, zeropage);
+
+		tprints("}");
+
+		break;
 	}
 
 	default:
 		return RVAL_DECODED;
 	}
+
+	return RVAL_DECODED | 1;
 }
 #endif /* HAVE_LINUX_USERFAULTFD_H */