From: Alan Cox <alan@linux.intel.com>
Date: Sat, 3 Jun 2017 23:02:46 +0000 (+0100)
Subject: execve: stop blocking in close_on_exec
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=467fbe2b4a204f7ed99382b36605ef0eb309051f;p=FUZIX.git

execve: stop blocking in close_on_exec

We don't allow closing of a dying process to block so in fact it's really
the same issue in the execve case. Dump all the ugly semaphore stuff for
a sanity check so we catch any offenders remaining after net was fixed
---

diff --git a/Kernel/include/kernel.h b/Kernel/include/kernel.h
index e0002a5c..d967f38f 100644
--- a/Kernel/include/kernel.h
+++ b/Kernel/include/kernel.h
@@ -300,6 +300,7 @@ struct mount {
 #define P_STOPPED       4    /* Sleeping, don't wake up for signal */
 #define P_FORKING       5    /* In process of forking; do not mess with */
 #define P_ZOMBIE        6    /* Exited. */
+#define P_NOSLEEP	7    /* In an internal state where sleep is forbidden */
 
 
 /* 0 is used to mean 'check we could signal this process' */
diff --git a/Kernel/process.c b/Kernel/process.c
index 3b103204..58a487e9 100644
--- a/Kernel/process.c
+++ b/Kernel/process.c
@@ -16,13 +16,13 @@
  * event equal to the process's own ptab address is a wait().
  */
 
+
 void psleep(void *event)
 {
 	irqflags_t irq = di();
 #ifdef DEBUG
 	kprintf("psleep(0x%p)", event);
 #endif
-
 	switch (udata.u_ptab->p_status) {
 	case P_SLEEP:		// echo output from devtty happens while processes are still sleeping but in-context
 	case P_STOPPED:		// coming to a halt
diff --git a/Kernel/syscall_exec16.c b/Kernel/syscall_exec16.c
index bdc4456a..46f7a296 100644
--- a/Kernel/syscall_exec16.c
+++ b/Kernel/syscall_exec16.c
@@ -86,8 +86,6 @@ static int header_ok(uint8_t *pp)
 	return 1;
 }
 
-static uint8_t in_execve;
-
 arg_t _execve(void)
 {
 	staticfast inoptr ino;
@@ -158,13 +156,7 @@ arg_t _execve(void)
 		goto nogood2;
 	}
 
-	/* We can't allow multiple execs to occur beyond this point at once
-	   otherwise we may deadlock out of buffers. As we already assume
-	   synchronous block I/O on 8bit boxes this isn't really a hit at all */
-	while(in_execve)
-		psleep(&in_execve);
-	in_execve = 1;
-
+	udata.u_ptab->p_status = P_NOSLEEP;
 	/* Gather the arguments, and put them in temporary buffers. */
 	abuf = (struct s_argblk *) tmpbuf();
 	/* Put environment in another buffer. */
@@ -262,19 +254,17 @@ arg_t _execve(void)
 	udata.u_isp = nenvp - 2;
 
 	// Start execution (never returns)
-	in_execve = 0;
-	wakeup(&in_execve);
+	udata.u_ptab->p_status = P_RUNNING;
 	doexec(progload);
 
 	// tidy up in various failure modes:
 nogood3:
+	udata.u_ptab->p_status = P_RUNNING;
 	brelse(abuf);
 	brelse(ebuf);
-	in_execve = 0;
-	wakeup(&in_execve);
-      nogood2:
+nogood2:
 	brelse(buf);
-      nogood:
+nogood:
 	i_deref(ino);
 	return (-1);
 }