This is a note to let you know that I've just added the patch titled
ionic: fix 16bit math issue when PAGE_SIZE >= 64KB
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ionic-fix-16bit-math-issue-when-page_size-64kb.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1a7cdefea68193762d727a59434102477ead6d6c
Author: David Christensen <drc@xxxxxxxxxxxxxxxxxx>
Date: Thu Sep 14 18:02:52 2023 -0400
ionic: fix 16bit math issue when PAGE_SIZE >= 64KB
[ Upstream commit 8f6b846b0a86c3cbae8a25b772651cfc2270ad0a ]
The ionic device supports a maximum buffer length of 16 bits (see
ionic_rxq_desc or ionic_rxq_sg_elem). When adding new buffers to
the receive rings, the function ionic_rx_fill() uses 16bit math when
calculating the number of pages to allocate for an RX descriptor,
given the interface's MTU setting. If the system PAGE_SIZE >= 64KB,
and the buf_info->page_offset is 0, the remain_len value will never
decrement from the original MTU value and the frag_len value will
always be 0, causing additional pages to be allocated as scatter-
gather elements unnecessarily.
A similar math issue exists in ionic_rx_frags(), but no failures
have been observed here since a 64KB page should not normally
require any scatter-gather elements at any legal Ethernet MTU size.
Fixes: 4b0a7539a372 ("ionic: implement Rx page reuse")
Signed-off-by: David Christensen <drc@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Shannon Nelson <shannon.nelson@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_dev.h b/drivers/net/ethernet/pensando/ionic/ionic_dev.h
index 922bb6c9e01d5..676c58dc19817 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_dev.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic_dev.h
@@ -174,6 +174,7 @@ typedef void (*ionic_desc_cb)(struct ionic_queue *q,
struct ionic_desc_info *desc_info,
struct ionic_cq_info *cq_info, void *cb_arg);
+#define IONIC_MAX_BUF_LEN ((u16)-1)
#define IONIC_PAGE_SIZE PAGE_SIZE
#define IONIC_PAGE_SPLIT_SZ (PAGE_SIZE / 2)
#define IONIC_PAGE_GFP_MASK (GFP_ATOMIC | __GFP_NOWARN |\
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
index 376f97b4008bb..6604f5862f892 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
@@ -151,7 +151,8 @@ static struct sk_buff *ionic_rx_frags(struct ionic_queue *q,
return NULL;
}
- frag_len = min_t(u16, len, IONIC_PAGE_SIZE - buf_info->page_offset);
+ frag_len = min_t(u16, len, min_t(u32, IONIC_MAX_BUF_LEN,
+ IONIC_PAGE_SIZE - buf_info->page_offset));
len -= frag_len;
dma_sync_single_for_cpu(dev,
@@ -388,7 +389,8 @@ void ionic_rx_fill(struct ionic_queue *q)
/* fill main descriptor - buf[0] */
desc->addr = cpu_to_le64(buf_info->dma_addr + buf_info->page_offset);
- frag_len = min_t(u16, len, IONIC_PAGE_SIZE - buf_info->page_offset);
+ frag_len = min_t(u16, len, min_t(u32, IONIC_MAX_BUF_LEN,
+ IONIC_PAGE_SIZE - buf_info->page_offset));
desc->len = cpu_to_le16(frag_len);
remain_len -= frag_len;
buf_info++;
@@ -407,7 +409,9 @@ void ionic_rx_fill(struct ionic_queue *q)
}
sg_elem->addr = cpu_to_le64(buf_info->dma_addr + buf_info->page_offset);
- frag_len = min_t(u16, remain_len, IONIC_PAGE_SIZE - buf_info->page_offset);
+ frag_len = min_t(u16, remain_len, min_t(u32, IONIC_MAX_BUF_LEN,
+ IONIC_PAGE_SIZE -
+ buf_info->page_offset));
sg_elem->len = cpu_to_le16(frag_len);
remain_len -= frag_len;
buf_info++;
