From: Alan Cox <alan@linux.intel.com>
Date: Wed, 22 Jun 2016 11:54:08 +0000 (+0100)
Subject: bank16k: fix bug reported by Brett
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=7b56e83c618ed3cdab4307ce2fc85667873ca75c;p=FUZIX.git

bank16k: fix bug reported by Brett
---

diff --git a/Kernel/bank16k.c b/Kernel/bank16k.c
index 0528686f..107abbcf 100644
--- 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;