From: Tom Zanussi <tom.zanussi@linux.intel.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: davem@davemloft.net, fenghua.yu@intel.com, vkoul@kernel.org,
dave.jiang@intel.com, tony.luck@intel.com,
wajdi.k.feghali@intel.com, james.guilford@intel.com,
kanchana.p.sridhar@intel.com, giovanni.cabiddu@intel.com,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
dmaengine@vger.kernel.org
Subject: Re: [PATCH v2 12/15] crypto: iaa - Add support for iaa_crypto deflate compression algorithm
Date: Thu, 06 Apr 2023 09:43:40 -0500 [thread overview]
Message-ID: <0b95f8b723f50395ee325ff5475e5d5189776928.camel@linux.intel.com> (raw)
In-Reply-To: <ZC58JggIXgpJ1tpD@gondor.apana.org.au>
Hi Herbert,
On Thu, 2023-04-06 at 16:00 +0800, Herbert Xu wrote:
> On Tue, Mar 28, 2023 at 10:35:32AM -0500, Tom Zanussi wrote:
> >
> > @@ -881,12 +1574,26 @@ static int iaa_crypto_probe(struct idxd_dev
> > *idxd_dev)
> >
> > rebalance_wq_table();
> >
> > + if (first_wq) {
> > + iaa_crypto_enabled = true;
> > + ret = iaa_register_compression_device();
> > + if (ret != 0) {
> > + iaa_crypto_enabled = false;
> > + dev_dbg(dev, "IAA compression device
> > registration failed\n");
> > + goto err_register;
> > + }
> > +
> > + pr_info("iaa_crypto now ENABLED\n");
> > + }
> > +
>
> Sorry for picking on your driver but I've got to start somewhere :)
No problem, thanks for reviewing the code. ;-)
>
> A long standing problem shared by almost all crypto drivers is that
> the hardware removal handling is completely broken.
>
> This is because hardware can be removed at any time, including during
> a crypto operatin. So drivers must work carefully around that fact.
>
> Here is a recipe for dealing with this safely:
>
> 1) Never unregister your crypto algorithms, even after the last
> piece of hardware has been unplugged. The algorithms should only
> be unregistered (if they have been registered through the first
> successful probe call) in the module unload function.
>
> 2) Never free any software state for your hardware without some form
> of synchronisation with oustanding operations.
>
> Any mechanism would do, for example, you could use a spinlock if the
> critical path isn't very long. The operational path would take the
> lock, check the hardware state, and if present proceed with the
> operation (but still being prepared to cope if the hardware goes
> AWAL because even if the driver state is still present the actual
> hardware may be gone already).
>
> Then the removal path would simply take the spinlock, set a flag
> indicating the hardware is gone and then you could safely unlock
> and free your driver states.
>
OK, yeah, thanks for pointing this out along with the detailed
explanation and remedy. Will take care of this in the next version.
Tom
> Thanks,
next prev parent reply other threads:[~2023-04-06 14:47 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 15:35 [PATCH v2 00/15] crypto: Add Intel Analytics Accelerator (IAA) crypto compression driver Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 01/15] dmaengine: idxd: add wq driver name support for accel-config user tool Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 02/15] dmaengine: idxd: add external module driver support for dsa_bus_type Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 03/15] dmaengine: idxd: Export drv_enable/disable and related functions Tom Zanussi
2023-03-28 16:02 ` Dave Jiang
2023-03-28 15:35 ` [PATCH v2 04/15] dmaengine: idxd: Export descriptor management functions Tom Zanussi
2023-03-28 16:04 ` Dave Jiang
2023-03-28 16:12 ` Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 05/15] dmaengine: idxd: Export wq resource " Tom Zanussi
2023-03-28 16:04 ` Dave Jiang
2023-03-28 15:35 ` [PATCH v2 06/15] dmaengine: idxd: Add private_data to struct idxd_wq Tom Zanussi
2023-03-28 16:06 ` Dave Jiang
2023-03-28 16:13 ` Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 07/15] dmaengine: idxd: add callback support for iaa crypto Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 08/15] crypto: iaa - Add IAA Compression Accelerator Documentation Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 09/15] crypto: iaa - Add Intel IAA Compression Accelerator crypto driver core Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 10/15] crypto: iaa - Add per-cpu workqueue table with rebalancing Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 11/15] crypto: iaa - Add compression mode management along with fixed mode Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 12/15] crypto: iaa - Add support for iaa_crypto deflate compression algorithm Tom Zanussi
2023-04-06 8:00 ` Herbert Xu
2023-04-06 14:43 ` Tom Zanussi [this message]
2023-03-28 15:35 ` [PATCH v2 13/15] crypto: iaa - Add support for default IAA 'canned' compression mode Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 14/15] crypto: iaa - Add irq support for the crypto async interface Tom Zanussi
2023-03-28 15:35 ` [PATCH v2 15/15] crypto: iaa - Add IAA Compression Accelerator stats Tom Zanussi
[not found] ` <20230329075149.2736-1-hdanton@sina.com>
2023-03-29 14:58 ` [PATCH v2 10/15] crypto: iaa - Add per-cpu workqueue table with rebalancing Tom Zanussi
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