From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Date: Thu, 27 Nov 2014 00:07:50 +0000 Subject: Re: [PATCH] dmaengine: rcar-dmac: Handle hardware descriptor allocation failure Message-Id: <1695373.od5H2ihtGp@avalon> List-Id: References: <1416924617-15939-1-git-send-email-j@bitron.ch> In-Reply-To: <1416924617-15939-1-git-send-email-j@bitron.ch> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: =?ISO-8859-1?Q?J=FCrg?= Billeter , Simon Horman Cc: Magnus Damm , Vinod Koul , Phil Edworthy , Kuninori Morimoto , linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org, dmaengine@vger.kernel.org Hi J=FCrg, Thank you for the patch. On Tuesday 25 November 2014 15:10:17 J=FCrg Billeter wrote: > If the atomic DMA coherent pool is too small, disable use of hardware > descriptor lists instead of crashing the system: >=20 > ERROR: 256 KiB atomic DMA coherent pool is too small! > Please increase it with coherent_pool=3D kernel parameter! >=20 > Unable to handle kernel NULL pointer dereference at virtual address 00000= 004 > Internal error: Oops: a07 [#1] PREEMPT SMP ARM >=20 > PC is at rcar_dmac_chan_reinit+0x3c/0x160 > LR is at _raw_spin_lock_irqsave+0x18/0x5c >=20 > [<802132c0>] (rcar_dmac_chan_reinit) from [<80214818>] > (rcar_dmac_isr_error+0x84/0xa0) [<80214818>] (rcar_dmac_isr_error) from > [<80060484>] (handle_irq_event_percpu+0x50/0x150) [<80060484>] > (handle_irq_event_percpu) from [<800605c0>] (handle_irq_event+0x3c/0x5c) > [<800605c0>] (handle_irq_event) from [<8006350c>] > (handle_fasteoi_irq+0xb8/0x198) [<8006350c>] (handle_fasteoi_irq) from > [<8005fdb0>] (generic_handle_irq+0x20/0x30) [<8005fdb0>] > (generic_handle_irq) from [<8000fcd0>] (handle_IRQ+0x50/0xc4) [<8000fcd0>] > (handle_IRQ) from [<800092cc>] (gic_handle_irq+0x28/0x5c) [<800092cc>] > (gic_handle_irq) from [<80012700>] (__irq_svc+0x40/0x70) >=20 > Kernel panic - not syncing: Fatal exception in interrupt >=20 > Signed-off-by: J=FCrg Billeter Acked-by: Laurent Pinchart and applied to my tree. > --- > drivers/dma/sh/rcar-dmac.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) >=20 > diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c > index f8f70eb..f18b1b6 100644 > --- a/drivers/dma/sh/rcar-dmac.c > +++ b/drivers/dma/sh/rcar-dmac.c > @@ -679,8 +679,8 @@ static void rcar_dmac_realloc_hwdesc(struct > rcar_dmac_chan *chan, desc->hwdescs.size =3D size; > } >=20 > -static void rcar_dmac_fill_hwdesc(struct rcar_dmac_chan *chan, > - struct rcar_dmac_desc *desc) > +static int rcar_dmac_fill_hwdesc(struct rcar_dmac_chan *chan, > + struct rcar_dmac_desc *desc) > { > struct rcar_dmac_xfer_chunk *chunk; > struct rcar_dmac_hw_desc *hwdesc; > @@ -689,7 +689,7 @@ static void rcar_dmac_fill_hwdesc(struct rcar_dmac_ch= an > *chan, >=20 > hwdesc =3D desc->hwdescs.mem; > if (!hwdesc) > - return; > + return -ENOMEM; >=20 > list_for_each_entry(chunk, &desc->chunks, node) { > hwdesc->sar =3D chunk->src_addr; > @@ -697,6 +697,8 @@ static void rcar_dmac_fill_hwdesc(struct rcar_dmac_ch= an > *chan, hwdesc->tcr =3D chunk->size >> desc->xfer_shift; > hwdesc++; > } > + > + return 0; > } >=20 > /* ---------------------------------------------------------------------= --- > @@ -933,8 +935,10 @@ rcar_dmac_chan_prep_sg(struct rcar_dmac_chan *chan, > struct scatterlist *sgl, * additional complexity remains to be > investigated. > */ > desc->hwdescs.use =3D !highmem && nchunks > 1; > - if (desc->hwdescs.use) > - rcar_dmac_fill_hwdesc(chan, desc); > + if (desc->hwdescs.use) { > + if (rcar_dmac_fill_hwdesc(chan, desc) < 0) > + desc->hwdescs.use =3D false; > + } >=20 > return &desc->async_tx; > } --=20 Regards, Laurent Pinchart