floppy: cleanup: make set_fdc() always set current_drive and current_fd

When called with a negative drive value, set_fdc() would stick to the
current fdc (which was assumed to reflect the current_drive's FDC). We
do not need this anymore as the last call place with a negative value
was just addressed. Let's make this function always set both current_fdc
and current_drive so that there's no more ambiguity. A few comments
stating this were added to a few non-obvious places.

Link: https://lore.kernel.org/r/20200410101904.14652-3-w@1wt.eu
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Denis Efremov <efremov@linux.com>

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 20646d4c54375c85c7d275ca0da3e7ceff450892..2817170dd403da48634d5c3139425fae6ec59379 100644 (file)
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -851,31 +851,42 @@ static void reset_fdc_info(int fdc, int mode)
                        drive_state[drive].track = NEED_2_RECAL;
 }
 
-/* selects the fdc and drive, and enables the fdc's input/dma. */
+/*
+ * selects the fdc and drive, and enables the fdc's input/dma.
+ * Both current_drive and current_fdc are changed to match the new drive.
+ */
 static void set_fdc(int drive)
 {
-       unsigned int new_fdc = current_fdc;
+       unsigned int fdc;
 
-       if (drive >= 0 && drive < N_DRIVE) {
-               new_fdc = FDC(drive);
-               current_drive = drive;
+       if (drive < 0 || drive >= N_DRIVE) {
+               pr_info("bad drive value %d\n", drive);
+               return;
        }
-       if (new_fdc >= N_FDC) {
+
+       fdc = FDC(drive);
+       if (fdc >= N_FDC) {
                pr_info("bad fdc value\n");
                return;
        }
-       current_fdc = new_fdc;
-       set_dor(current_fdc, ~0, 8);
+
+       set_dor(fdc, ~0, 8);
 #if N_FDC > 1
-       set_dor(1 - current_fdc, ~8, 0);
+       set_dor(1 - fdc, ~8, 0);
 #endif
-       if (fdc_state[current_fdc].rawcmd == 2)
-               reset_fdc_info(current_fdc, 1);
-       if (fdc_inb(current_fdc, FD_STATUS) != STATUS_READY)
-               fdc_state[current_fdc].reset = 1;
+       if (fdc_state[fdc].rawcmd == 2)
+               reset_fdc_info(fdc, 1);
+       if (fdc_inb(fdc, FD_STATUS) != STATUS_READY)
+               fdc_state[fdc].reset = 1;
+
+       current_drive = drive;
+       current_fdc = fdc;
 }
 
-/* locks the driver */
+/*
+ * locks the driver.
+ * Both current_drive and current_fdc are changed to match the new drive.
+ */
 static int lock_fdc(int drive)
 {
        if (WARN(atomic_read(&usage_count) == 0,
@@ -3000,6 +3011,10 @@ static const struct cont_t reset_cont = {
        .done           = generic_done
 };
 
+/*
+ * Resets the FDC connected to drive <drive>.
+ * Both current_drive and current_fdc are changed to match the new drive.
+ */
 static int user_reset_fdc(int drive, int arg, bool interruptible)
 {
        int ret;