From e55ace0f517ede6f3635341c8adadc7b90aa75c5 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 16 Apr 2022 18:31:21 +0200
Subject: kernel/vfs: be more strict about the state of `vfs_backend.handler`

---
 src/kernel/syscalls.c    | 1 +
 src/kernel/vfs/request.c | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 31bd0de..b424bf1 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -206,6 +206,7 @@ int _syscall_fs_wait(char __user *buf, int max_len, struct fs_wait_response __us
 	if (!backend) return -1;
 
 	process_transition(process_current, PS_WAITS4REQUEST);
+	assert(!backend->handler); // TODO allow multiple processes to wait on the same backend
 	backend->handler = process_current;
 	/* checking the validity of those pointers here would make
 	 * vfs_request_accept simpler. TODO? */
diff --git a/src/kernel/vfs/request.c b/src/kernel/vfs/request.c
index 277c353..ad72264 100644
--- a/src/kernel/vfs/request.c
+++ b/src/kernel/vfs/request.c
@@ -21,9 +21,8 @@ int vfs_request_create(struct vfs_request req_) {
 		case VFS_BACK_ROOT:
 			return vfs_root_handler(req);
 		case VFS_BACK_USER:
-			if (req->backend->handler
-					&& req->backend->handler->state == PS_WAITS4REQUEST)
-			{
+			if (req->backend->handler) {
+				assert(req->backend->handler->state == PS_WAITS4REQUEST);
 				vfs_request_accept(req);
 			} else {
 				// backend isn't ready yet, join the queue
@@ -65,6 +64,7 @@ int vfs_request_accept(struct vfs_request *req) {
 
 	process_transition(handler, PS_RUNNING);
 	handler->handled_req = req;
+	req->backend->handler = NULL;
 	regs_savereturn(&handler->regs, 0);
 	return 0;
 fail:
-- 
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