mISDN: fix a loop count

There are two issue here.
1)  cnt starts as maxloop + 1 so all these loops iterate one more time
    than intended.
2)  At the end of the loop we test for "if (maxloop && !cnt)" but for
    the first two loops, we end with cnt equal to -1.  Changing this to
    a pre-op means we end with cnt set to 0.

Fixes: cae86d4a4e56 ('mISDN: Add driver for Infineon ISDN chipset family')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 4 deletions

diff --git a/drivers/isdn/hardware/mISDN/mISDNipac.c b/drivers/isdn/hardware/mISDN/mISDNipac.c
index a77eea594b69..cb428b9ee441 100644
--- a/drivers/isdn/hardware/mISDN/mISDNipac.c
+++ b/drivers/isdn/hardware/mISDN/mISDNipac.c
@@ -1170,7 +1170,7 @@ mISDNipac_irq(struct ipac_hw *ipac, int maxloop)
 
         if (ipac->type & IPAC_TYPE_IPACX) {
                 ista = ReadIPAC(ipac, ISACX_ISTA);
-                while (ista && cnt--) {
+                while (ista && --cnt) {
                         pr_debug("%s: ISTA %02x\n", ipac->name, ista);
                         if (ista & IPACX__ICA)
                                 ipac_irq(&ipac->hscx[0], ista);
@@ -1182,7 +1182,7 @@ mISDNipac_irq(struct ipac_hw *ipac, int maxloop)
                 }
         } else if (ipac->type & IPAC_TYPE_IPAC) {
                 ista = ReadIPAC(ipac, IPAC_ISTA);
-                while (ista && cnt--) {
+                while (ista && --cnt) {
                         pr_debug("%s: ISTA %02x\n", ipac->name, ista);
                         if (ista & (IPAC__ICD | IPAC__EXD)) {
                                 istad = ReadISAC(isac, ISAC_ISTA);
@@ -1200,7 +1200,7 @@ mISDNipac_irq(struct ipac_hw *ipac, int maxloop)
                         ista = ReadIPAC(ipac, IPAC_ISTA);
                 }
         } else if (ipac->type & IPAC_TYPE_HSCX) {
-                while (cnt) {
+                while (--cnt) {
                         ista = ReadIPAC(ipac, IPAC_ISTAB + ipac->hscx[1].off);
                         pr_debug("%s: B2 ISTA %02x\n", ipac->name, ista);
                         if (ista)
@@ -1211,7 +1211,6 @@ mISDNipac_irq(struct ipac_hw *ipac, int maxloop)
                                 mISDNisac_irq(isac, istad);
                         if (0 == (ista | istad))
                                 break;
-                        cnt--;
                 }
         }
         if (cnt > maxloop) /* only for ISAC/HSCX without PCI IRQ test */