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From: "Pai G, Sunil" <sunil.pai.g@intel.com>
To: "Richardson, Bruce" <bruce.richardson@intel.com>,
	"dev@dpdk.org" <dev@dpdk.org>
Cc: "Richardson, Bruce" <bruce.richardson@intel.com>,
	"Laatz, Kevin" <kevin.laatz@intel.com>,
	"stable@dpdk.org" <stable@dpdk.org>,
	"Hu, Jiayu" <jiayu.hu@intel.com>
Subject: RE: [PATCH] dma/idxd: fix burst capacity calculation
Date: Mon, 10 Jan 2022 13:09:02 +0000	[thread overview]
Message-ID: <DM8PR11MB5605F2B8DFA7B6D84270F9E8BD509@DM8PR11MB5605.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20211220170514.736732-1-bruce.richardson@intel.com>

Hi Bruce, Kevin

This patch seems to have uncovered a bug in the driver.
On applying, the idxd_burst_capacity API seems to return 0 for cases even when there are batch descriptors and ring space available.
Seems like there is a wraparound missing when calculating the descriptor ring space, causing this behavior.  

Below change seems to fix the issue.

@@ -483,7 +496,7 @@ idxd_burst_capacity(const void *dev_private, uint16_t vchan __rte_unused)
        /* 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;                                         
+       used_space = (write_idx - idxd->ids_returned)&idxd->desc_ring_mask;                  

<snipped>

Could we include this fix in the current patch ?

Thanks and regards,
Sunil

  parent reply	other threads:[~2022-01-10 13:09 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-20 17:05 Bruce Richardson
2022-01-04 17:16 ` Kevin Laatz
2022-01-05  1:32   ` Hu, Jiayu
2022-01-10 13:09 ` Pai G, Sunil [this message]
2022-01-10 13:25   ` Bruce Richardson
2022-01-10 13:44     ` Pai G, Sunil
2022-01-10 16:18       ` Bruce Richardson
2022-01-11 13:41 ` [PATCH v2 0/4] fixes for dma/idxd Bruce Richardson
2022-01-11 13:41   ` [PATCH v2 1/4] dma/idxd: fix burst capacity calculation 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   ` [PATCH v2 3/4] dma/idxd: fix wrap-around in burst capacity calculation Bruce Richardson
2022-01-11 13:45     ` Pai G, Sunil
2022-01-11 16:50     ` Kevin Laatz
2022-01-11 13:41   ` [PATCH v2 4/4] test_dmadev: increase iterations of capacity test case Bruce Richardson
2022-01-11 16:50     ` Kevin Laatz
2022-01-20 13:06   ` [PATCH v2 0/4] fixes for dma/idxd Thomas Monjalon

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