From e17137d8d74e65e3cce7c04263d73a111bae25c0 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 9 Apr 2022 18:55:22 +0200
Subject: kernel: `vfs_request_accept` now doesn't switch processes

---
 src/kernel/proc.c        |  1 +
 src/kernel/syscalls.c    |  4 ++--
 src/kernel/vfs/request.c | 12 +++++++-----
 src/kernel/vfs/request.h |  4 ++--
 4 files changed, 12 insertions(+), 9 deletions(-)

(limited to 'src/kernel')

diff --git a/src/kernel/proc.c b/src/kernel/proc.c
index e67af19..d20b0d3 100644
--- a/src/kernel/proc.c
+++ b/src/kernel/proc.c
@@ -58,6 +58,7 @@ struct process *process_fork(struct process *parent) {
 }
 
 void process_switch(struct process *proc) {
+	assert(proc->state == PS_RUNNING);
 	process_current = proc;
 	pagedir_switch(proc->pages);
 	sysexit(proc->regs);
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index daf7cac..855fad8 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -207,7 +207,7 @@ int _syscall_fs_wait(char __user *buf, int max_len, struct fs_wait_response __us
 	process_current->state = PS_WAITS4REQUEST;
 	backend->handler = process_current;
 	/* checking the validity of those pointers here would make
-	 * vfs_request_pass2handler simpler. TODO? */
+	 * vfs_request_accept simpler. TODO? */
 	process_current->awaited_req.buf     = buf;
 	process_current->awaited_req.max_len = max_len;
 	process_current->awaited_req.res     = res;
@@ -216,7 +216,7 @@ int _syscall_fs_wait(char __user *buf, int max_len, struct fs_wait_response __us
 		// handle queued requests
 		struct process *queued = backend->queue;
 		backend->queue = queued->waits4fs.queue_next;
-		vfs_request_pass2handler(&queued->waits4fs.req);
+		return vfs_request_accept(&queued->waits4fs.req);
 	} else {
 		process_switch_any();
 	}
diff --git a/src/kernel/vfs/request.c b/src/kernel/vfs/request.c
index 761b619..ecd862a 100644
--- a/src/kernel/vfs/request.c
+++ b/src/kernel/vfs/request.c
@@ -28,7 +28,8 @@ int vfs_request_create(struct vfs_request req_) {
 			if (req->backend->handler
 					&& req->backend->handler->state == PS_WAITS4REQUEST)
 			{
-				vfs_request_pass2handler(req);
+				vfs_request_accept(req);
+				process_switch(req->backend->handler);
 			} else {
 				// backend isn't ready yet, join the queue
 				struct process **iter = &req->backend->queue;
@@ -42,18 +43,17 @@ int vfs_request_create(struct vfs_request req_) {
 	}
 }
 
-_Noreturn void vfs_request_pass2handler(struct vfs_request *req) {
+int vfs_request_accept(struct vfs_request *req) {
 	struct process *handler = req->backend->handler;
 	struct fs_wait_response res = {0};
 	int len;
 	assert(handler);
 	assert(handler->state == PS_WAITS4REQUEST); // TODO currently callers have to ensure that the handler is in the correct state. should they?
 	assert(!handler->handled_req);
-	handler->state = PS_RUNNING;
-	handler->handled_req = req;
 
 	len = min(req->input.len, handler->awaited_req.max_len);
 
+	// TODO having to separately handle copying from kernel and userland stinks
 	if (req->input.kern) {
 		if (!virt_cpy_to(handler->pages,
 					handler->awaited_req.buf, req->input.buf_kern, len))
@@ -74,8 +74,10 @@ _Noreturn void vfs_request_pass2handler(struct vfs_request *req) {
 				handler->awaited_req.res, &res, sizeof res))
 		goto fail; // can't copy response struct
 
+	handler->state = PS_RUNNING;
+	handler->handled_req = req;
 	regs_savereturn(&handler->regs, 0);
-	process_switch(handler);
+	return;
 fail:
 	panic_unimplemented(); // TODO
 }
diff --git a/src/kernel/vfs/request.h b/src/kernel/vfs/request.h
index 0e96db6..2bcaae6 100644
--- a/src/kernel/vfs/request.h
+++ b/src/kernel/vfs/request.h
@@ -41,7 +41,7 @@ struct vfs_request {
 };
 
 /** Assigns the vfs_request to the caller, and calls the backend. Might not
- * return - can switch processes! */
+ * return - can switch processes! TODO no it can't*/
 int vfs_request_create(struct vfs_request);
-_Noreturn void vfs_request_pass2handler(struct vfs_request *);
+int vfs_request_accept(struct vfs_request *);
 int vfs_request_finish(struct vfs_request *, int ret);
-- 
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