Re: use exact allocation for dma coherent memory

From: Dan Carpenter <dan.carpenter@oracle.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
	devel@driverdev.osuosl.org, linux-s390@vger.kernel.org,
	linux-rdma@vger.kernel.org, David Airlie <airlied@linux.ie>,
	linux-media@vger.kernel.org,
	Intel Linux Wireless <linuxwifi@intel.com>,
	intel-gfx@lists.freedesktop.org,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Ian Abbott <abbotti@mev.co.uk>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Sean Paul <sean@poorly.run>,
	"moderated list:ARM PORT" <linux-arm-kernel@lists.infradead.org>,
	netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	H Hartley Sweeten <hsweeten@visionengravers.com>,
	iommu@lists.linux-foundation.org, Daniel Vetter <daniel@ffwll.ch>
Subject: Re: use exact allocation for dma coherent memory
Date: Mon, 17 Jun 2019 11:21:48 +0300	[thread overview]
Message-ID: <20190617082148.GF28859@kadam> (raw)
In-Reply-To: <20190614134726.3827-1-hch@lst.de>

I once wrote a Smatch check based on a commit message that said we can't
pass dma_alloc_coherent() pointers to virt_to_phys().  But then I never
felt like I understood the rules enough to actually report the warnings
as bugs.

drivers/platform/x86/dcdbas.c:108 smi_data_buf_realloc() error: 'buf' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/net/caif/caif_virtio.c:414 cfv_create_genpool() error: 'cfv->alloc_addr' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/cxgb4/qp.c:135 alloc_host_sq() error: 'sq->queue' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/cxgb4/qp.c:272 create_qp() error: 'wq->rq.queue' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/cxgb4/qp.c:2628 alloc_srq_queue() error: 'wq->queue' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/ocrdma/ocrdma_verbs.c:494 ocrdma_alloc_ucontext() error: 'ctx->ah_tbl.va' came from dma_alloc_coherent() so we can't do virt_to_phys()

drivers/infiniband/hw/cxgb4/qp.c
   129  static int alloc_host_sq(struct c4iw_rdev *rdev, struct t4_sq *sq)
   130  {
   131          sq->queue = dma_alloc_coherent(&(rdev->lldi.pdev->dev), sq->memsize,
   132                                         &(sq->dma_addr), GFP_KERNEL);
   133          if (!sq->queue)
   134                  return -ENOMEM;
   135          sq->phys_addr = virt_to_phys(sq->queue);
   136          dma_unmap_addr_set(sq, mapping, sq->dma_addr);
   137          return 0;
   138  }

Is this a bug?

regards,
dan carpenter

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