s390/qdio: for_each macro correctness

I observed that there are for_each macros that do an extra memory access
beyond the defined area.
Normally this does not cause problems.
But, this can cause exceptions. For example: if the area is allocated at
the end of a page and the next page is not accessible.

For correctness, I suggest changing the arguments of the 'for loop' like
others 'for_each' do in the kernel.

Signed-off-by: Jose Alonso <joalonsof@gmail.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 6 insertions, 8 deletions

diff --git a/drivers/s390/cio/qdio.h b/drivers/s390/cio/qdio.h
index 8acaae18bd11..a563e4c00590 100644
--- a/drivers/s390/cio/qdio.h
+++ b/drivers/s390/cio/qdio.h
@@ -359,14 +359,12 @@ static inline int multicast_outbound(struct qdio_q *q)
 #define need_siga_sync_out_after_pci(q) \
         (unlikely(q->irq_ptr->siga_flag.sync_out_after_pci))
 
-#define for_each_input_queue(irq_ptr, q, i)     \
-        for (i = 0, q = irq_ptr->input_qs[0];   \
-                i < irq_ptr->nr_input_qs;       \
-                q = irq_ptr->input_qs[++i])
-#define for_each_output_queue(irq_ptr, q, i)    \
-        for (i = 0, q = irq_ptr->output_qs[0];  \
-                i < irq_ptr->nr_output_qs;      \
-                q = irq_ptr->output_qs[++i])
+#define for_each_input_queue(irq_ptr, q, i)             \
+        for (i = 0; i < irq_ptr->nr_input_qs &&         \
+                ({ q = irq_ptr->input_qs[i]; 1; }); i++)
+#define for_each_output_queue(irq_ptr, q, i)            \
+        for (i = 0; i < irq_ptr->nr_output_qs &&        \
+                ({ q = irq_ptr->output_qs[i]; 1; }); i++)
 
 #define prev_buf(bufnr) \
         ((bufnr + QDIO_MAX_BUFFERS_MASK) & QDIO_MAX_BUFFERS_MASK)