process: fix a race in SIGSTOP handling and slightly optimize newproc

diff --git a/Kernel/process.c b/Kernel/process.c
index 3b042d9..bb96b81 100644 (file)
--- a/Kernel/process.c
+++ b/Kernel/process.c
@@ -216,6 +216,9 @@ void newproc(ptptr p)
        if (!p->p_tty)          /* If no tty, try tty of parent's parent */
                p->p_tty = udata.u_ptab->p_pptr->p_tty;
        p->p_uid = udata.u_ptab->p_uid;
+       /* Set default priority */
+       p->p_priority = MAXTICKS;
+
        udata.u_ptab = p;
 
        memset(&udata.u_utime, 0, 4 * sizeof(clock_t)); /* Clear tick counters */
@@ -227,10 +230,6 @@ void newproc(ptptr p)
                i_ref(udata.u_root);
        udata.u_cursig = 0;
        udata.u_error = 0;
-
-       /* Set default priority */
-       p->p_priority = MAXTICKS;
-
        for (j = udata.u_files; j < (udata.u_files + UFTSIZE); ++j) {
                if (*j != NO_FILE)
                        ++of_tab[*j].o_refs;
@@ -461,6 +460,8 @@ uint8_t chksigs(void)
        /* Fast path - no signals pending means no work.
           Cursig being set means we've already worked out what to do.
         */
+
+rescan:
        if (udata.u_cursig || !pending || udata.u_ptab->p_status == P_STOPPED)
                return udata.u_cursig;
 
@@ -487,6 +488,8 @@ uint8_t chksigs(void)
                                udata.u_ptab->p_pending &= ~m;  // unset the bit
                                irqrestore(irq);
                                switchout();
+                               /* Other things may have happened */
+                               goto rescan;
                        }
                        if ((m & clear) || udata.u_ptab->p_pid == 1) {
                        /* SIGCONT is subtle - we woke the process to handle