bank16k: fix bug reported by Brett

diff --git a/Kernel/bank16k.c b/Kernel/bank16k.c
index 0528686..107abbc 100644 (file)
--- a/Kernel/bank16k.c
+++ b/Kernel/bank16k.c
@@ -111,45 +111,51 @@ int pagemap_alloc(ptptr p)
  */
 int pagemap_realloc(usize_t size)
 {
-       int have = maps_needed(udata.u_top);
-       int want = maps_needed(size);
+       int8_t have = maps_needed(udata.u_top);
+       int8_t want = maps_needed(size);
        uint8_t *ptr = (uint8_t *) & udata.u_page;
-       int i;
+       int8_t i;
+       uint8_t update = 0;
        irqflags_t irq;
 
        /* If we are shrinking then free pages and propogate the
           common page into the freed spaces */
        if (want == have)
                return 0;
-       if (have > want) {
-               for (i = want; i < have; i++) {
-                       pfree[pfptr++] = ptr[i];
-                       ptr[i] = ptr[3];
-               }
-               udata.u_ptab->p_page = udata.u_page;
-               udata.u_ptab->p_page2 = udata.u_page2;
-               return 0;
-       }
 
-       /* If we are adding then just insert the new pages, keeping the common
-          unchanged at the top */
-       if (want - have > pfptr)
-               return ENOMEM;
        /* We don't want to take an interrupt here while our page mappings are
           incomplete. We may restore bogus mappings and then take a second IRQ
           into hyperspace */
-        irq = di();
+       irq = di();
+
+       if (have > want) {
+               for (i = want; i < have; i++) {
+                       pfree[pfptr++] = ptr[i - 1];
+                       ptr[i - 1] = ptr[3];
+               }
+               /* We collapsed top and bottom, so we need to sort our vectors
+                  and common space out */
+               if (want == 1)
+                       update = 1;
+       } else if (want - have <= pfptr) {
+               /* If we are adding then just insert the new pages, keeping the common
+                  unchanged at the top */
+               for (i = have; i < want; i++)
+                       ptr[i - 1] = pfree[--pfptr];
+               update = 1;
 
-       for (i = have; i < want; i++)
-               ptr[i - 1] = pfree[--pfptr];
+       } else {
+               irqrestore(irq);
+               return ENOMEM;
+       }
        /* Copy the updated allocation into the ptab */
        udata.u_ptab->p_page = udata.u_page;
        udata.u_ptab->p_page2 = udata.u_page2;
        /* Now fix the vectors up - they've potentially teleported up to 48K up
           the user address space, we need to put a copy back in low memory before
           we switch to this memory map */
-       program_vectors(&udata.u_page);
-
+       if (update)
+               program_vectors(&udata.u_page);
        irqrestore(irq);
        return 0;
 }
@@ -177,7 +183,7 @@ int swapout(ptptr p)
        uint16_t base = SWAPBASE;
        uint16_t size = (0x4000 - SWAPBASE) >> 9;
        uint16_t i;
-       uint8_t *pt = (uint8_t *)&p->p_page;
+       uint8_t *pt = (uint8_t *) & p->p_page;
 
        if (!page)
                panic(PANIC_ALREADYSWAP);
@@ -192,10 +198,10 @@ int swapout(ptptr p)
        blk = map * SWAP_SIZE;
        /* Write the app (and possibly the uarea etc..) to disk */
        for (i = 0; i < 4; i++) {
-               swapwrite(SWAPDEV, blk, size<<9, base, *pt++);
+               swapwrite(SWAPDEV, blk, size << 9, base, *pt++);
                base += 0x4000;
                base &= 0xC000; /* Snap to bank alignment */
-                blk += size;
+               blk += size;
                /* Last bank is determined by SWAP SIZE. We do the maths
                   in 512's (0x60 = 0xC000) */
                if (i == 2)
@@ -224,7 +230,7 @@ void swapin(ptptr p, uint16_t map)
        uint16_t base = SWAPBASE;
        uint16_t size = (0x4000 - SWAPBASE) >> 9;
        uint16_t i;
-       uint8_t *pt = (uint8_t *)&p->p_page;
+       uint8_t *pt = (uint8_t *) & p->p_page;
 
 #ifdef DEBUG
        kprintf("Swapin %x, %d\n", p, p->p_page);
@@ -234,8 +240,8 @@ void swapin(ptptr p, uint16_t map)
                return;
        }
 
-       for (i = 0; i < 4; i ++) {
-               swapread(SWAPDEV, blk, size<<9, base, *pt++);
+       for (i = 0; i < 4; i++) {
+               swapread(SWAPDEV, blk, size << 9, base, *pt++);
                base += 0x4000;
                base &= 0xC000;
                blk += size;