RE: RE: [PATCH] be2net: Bugfix for packet drop with kernel param swiotlb=force

-----Original Message-----
From: jiang.biao2@zte.com.cn [mailto:jiang.biao2@zte.com.cn]

quoted

quoted

From: Li Fengmao <redacted>

There will be packet drop with kernel param "swiotlb = force" on
Emulex 10Gb NIC using be2net driver. The problem is caused by
receiving skb without calling pci_unmap_page() in get_rx_page_info().
rx_page_info->last_page_user is initialized to false in
be_post_rx_frags() when current frag are mapped in the first half of
the same page with another frag. But in that case with
"swiotlb = force" param, data can not be copied into the page of
rx_page_info without calling pci_unmap_page, so the data frag mapped
in the first half of the page will be dropped.

It can be solved by creating only a mapping relation between frag
and page, and deleting rx_page_info->last_page_user to ensure
calling pci_unmap_page when handling each receiving frag.

This patch uses an entire page for each RX frag (whose default size is 2048).
Consequently, on platforms like ppc64 where the default PAGE_SIZE is 64K,
memory usage becomes very inefficient.

Instead, I've tried a partial-page mapping scheme. This retains the
page sharing logic, but un-maps each frag separately so that
the data is copied from the bounce buffers.

Pls see if this works for you;  thanks.

Our patch indeed has some problem because use an entire page by alloc_pages，
maybe kmalloc should be appropriate.
Your modification works for us, it should be a right patch for the bug.

Thanks for verifying. I'll re-post my patch with a proper sign-off.

-Sathya