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From: Jason Gunthorpe <jgg@mellanox.com>
To: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Cc: "kenneth.w.graunke@intel.com" <kenneth.w.graunke@intel.com>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"sanjay.k.kumar@intel.com" <sanjay.k.kumar@intel.com>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"jason.ekstrand@intel.com" <jason.ekstrand@intel.com>,
	"dave.hansen@intel.com" <dave.hansen@intel.com>,
	"jglisse@redhat.com" <jglisse@redhat.com>,
	"daniel.vetter@intel.com" <daniel.vetter@intel.com>,
	"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
	"ira.weiny@intel.com" <ira.weiny@intel.com>
Subject: Re: [Intel-gfx] [RFC v2 02/12] drm/i915/svm: Runtime (RT) allocator support
Date: Tue, 17 Dec 2019 20:18:21 +0000	[thread overview]
Message-ID: <20191217201815.GF16762@mellanox.com> (raw)
In-Reply-To: <20191213215614.24558-3-niranjana.vishwanathapura@intel.com>

On Fri, Dec 13, 2019 at 01:56:04PM -0800, Niranjana Vishwanathapura wrote:
  
> +	ctx = i915_gem_context_lookup(file->driver_priv, args->rsvd1);
> +	if (!ctx || !rcu_access_pointer(ctx->vm))
> +		return -ENOENT;
> +
> +	rcu_read_lock();
> +	vm = i915_vm_get(ctx->vm);
> +	rcu_read_unlock();

This looks like wrong use of RCU to me.

Getting a rcu lock and not calling rcu_dereference under it is
basically guarenteed to be wrong..

Jason
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  parent reply	other threads:[~2019-12-17 20:18 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-13 21:56 [Intel-gfx] [RFC v2 00/12] drm/i915/svm: Add SVM support Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 01/12] drm/i915/svm: Add SVM documentation Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 02/12] drm/i915/svm: Runtime (RT) allocator support Niranjana Vishwanathapura
2019-12-13 22:58   ` Jason Ekstrand
2019-12-13 23:13     ` Niranjan Vishwanathapura
2019-12-14  0:36       ` Jason Ekstrand
2019-12-14 10:31         ` Chris Wilson
2019-12-16  4:13           ` Niranjan Vishwanathapura
2019-12-17 18:01             ` Jason Ekstrand
2019-12-18 23:25               ` Niranjana Vishwanathapura
2019-12-14 10:56   ` Chris Wilson
2019-12-16  4:15     ` Niranjan Vishwanathapura
2019-12-18 22:51       ` Niranjana Vishwanathapura
2019-12-17 20:18   ` Jason Gunthorpe [this message]
2019-12-18 23:34     ` Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 03/12] drm/i915/svm: Implicitly migrate BOs upon CPU access Niranjana Vishwanathapura
2019-12-14 10:58   ` Chris Wilson
2019-12-16  4:17     ` Niranjan Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 04/12] drm/i915/svm: Page table update support for SVM Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 05/12] drm/i915/svm: Page table mirroring support Niranjana Vishwanathapura
2019-12-17 20:31   ` Jason Gunthorpe
2019-12-18 22:41     ` Niranjana Vishwanathapura
2019-12-20 13:45       ` Jason Gunthorpe
2019-12-22 19:54         ` Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 06/12] drm/i915/svm: Device memory support Niranjana Vishwanathapura
2019-12-17 20:35   ` Jason Gunthorpe
2019-12-18 22:15     ` Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 07/12] drm/i915/svm: Implicitly migrate pages upon CPU fault Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 08/12] drm/i915/svm: Page copy support during migration Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 09/12] drm/i915/svm: Add functions to blitter copy SVM buffers Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 10/12] drm/i915/svm: Use blitter copy for migration Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 11/12] drm/i915/svm: Add support to en/disable SVM Niranjana Vishwanathapura
2019-12-13 21:56 ` [Intel-gfx] [RFC v2 12/12] drm/i915/svm: Add page table dump support Niranjana Vishwanathapura
2019-12-14  1:32 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for drm/i915/svm: Add SVM support (rev2) Patchwork
2020-01-24  8:42 ` [Intel-gfx] [RFC v2 00/12] drm/i915/svm: Add SVM support Niranjana Vishwanathapura

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