[PATCH] uml: clean arch_switch usage

[pandora-kernel.git] / arch / um / kernel / tt / process_kern.c

diff --git a/arch/um/kernel/tt/process_kern.c b/arch/um/kernel/tt/process_kern.c
index 295c1ac..a9c1443 100644 (file)
--- a/arch/um/kernel/tt/process_kern.c
+++ b/arch/um/kernel/tt/process_kern.c
@@ -51,6 +51,13 @@ void switch_to_tt(void *prev, void *next)
 
        c = 0;
 
+       /* Notice that here we "up" the semaphore on which "to" is waiting, and
+        * below (the read) we wait on this semaphore (which is implemented by
+        * switch_pipe) and go sleeping. Thus, after that, we have resumed in
+        * "to", and can't use any more the value of "from" (which is outdated),
+        * nor the value in "to" (since it was the task which stole us the CPU,
+        * which we don't care about). */
+
        err = os_write_file(to->thread.mode.tt.switch_pipe[1], &c, sizeof(c));
        if(err != sizeof(c))
                panic("write of switch_pipe failed, err = %d", -err);
@@ -77,7 +84,7 @@ void switch_to_tt(void *prev, void *next)
        change_sig(SIGALRM, alrm);
        change_sig(SIGPROF, prof);
 
-       arch_switch();
+       arch_switch_to_tt(prev_sched, current);
 
        flush_tlb_all();
        local_irq_restore(flags);
@@ -141,7 +148,6 @@ static void new_thread_handler(int sig)
        set_cmdline("(kernel thread)");
 
        change_sig(SIGUSR1, 1);
-       change_sig(SIGVTALRM, 1);
        change_sig(SIGPROF, 1);
        local_irq_enable();
        if(!run_kernel_thread(fn, arg, &current->thread.exec_buf))