From: Bruce Richardson <bruce.richardson@intel.com>
To: dev@dpdk.org
Cc: Bruce Richardson <bruce.richardson@intel.com>,
kevin.laatz@intel.com, stable@dpdk.org,
Sunil Pai G <sunil.pai.g@intel.com>,
Conor Walsh <conor.walsh@intel.com>,
Chengwen Feng <fengchengwen@huawei.com>
Subject: [PATCH v2 3/4] dma/idxd: fix wrap-around in burst capacity calculation
Date: Tue, 11 Jan 2022 13:41:04 +0000 [thread overview]
Message-ID: <20220111134105.1007191-4-bruce.richardson@intel.com> (raw)
In-Reply-To: <20220111134105.1007191-1-bruce.richardson@intel.com>
The burst capacity calculation code assumes that the write and read
(i.e. ids_returned) values both wrap at the ring-size, but the read
value instead wraps as UINT16_MAX. Therefore, instead of just adding
ring-size to the write value in case the read is greater, we need to
just always mask the result to ensure a correct, in-range, value.
Fixes: 9459de4edc99 ("dma/idxd: add burst capacity")
Cc: kevin.laatz@intel.com
Cc: stable@dpdk.org
Reported-by: Sunil Pai G <sunil.pai.g@intel.com>
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
drivers/dma/idxd/idxd_common.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/dma/idxd/idxd_common.c b/drivers/dma/idxd/idxd_common.c
index 4442d1cbbd..ea6413cc7a 100644
--- a/drivers/dma/idxd/idxd_common.c
+++ b/drivers/dma/idxd/idxd_common.c
@@ -480,10 +480,8 @@ idxd_burst_capacity(const void *dev_private, uint16_t vchan __rte_unused)
idxd->batch_idx_write + 1 == idxd->batch_idx_read)
return 0;
- /* For descriptors, check for wrap-around on write but not read */
- if (idxd->ids_returned > write_idx)
- write_idx += idxd->desc_ring_mask + 1;
- used_space = write_idx - idxd->ids_returned;
+ /* Subtract and mask to get in correct range */
+ used_space = (write_idx - idxd->ids_returned) & idxd->desc_ring_mask;
const int ret = RTE_MIN((idxd->desc_ring_mask - used_space),
(idxd->max_batch_size - idxd->batch_size));
--
2.32.0
next prev parent reply other threads:[~2022-01-11 13:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 17:05 [PATCH] dma/idxd: fix " Bruce Richardson
2022-01-04 17:16 ` Kevin Laatz
2022-01-05 1:32 ` Hu, Jiayu
2022-01-10 13:09 ` Pai G, Sunil
2022-01-10 13:25 ` Bruce Richardson
2022-01-10 13:44 ` Pai G, Sunil
2022-01-10 16:18 ` Bruce Richardson
[not found] ` <20220111134105.1007191-1-bruce.richardson@intel.com>
2022-01-11 13:41 ` [PATCH v2 1/4] " Bruce Richardson
2022-01-11 13:41 ` [PATCH v2 2/4] dma/idxd: fix paths to driver sysfs directory Bruce Richardson
2022-01-11 16:50 ` Kevin Laatz
2022-01-11 13:41 ` Bruce Richardson [this message]
2022-01-11 13:45 ` [PATCH v2 3/4] dma/idxd: fix wrap-around in burst capacity calculation Pai G, Sunil
2022-01-11 16:50 ` Kevin Laatz
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220111134105.1007191-4-bruce.richardson@intel.com \
--to=bruce.richardson@intel.com \
--cc=conor.walsh@intel.com \
--cc=dev@dpdk.org \
--cc=fengchengwen@huawei.com \
--cc=kevin.laatz@intel.com \
--cc=stable@dpdk.org \
--cc=sunil.pai.g@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).