| Message ID | 1288137180-3220-5-git-send-email-yanok@emcraft.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Grant Likely |
| Headers | show |
On Wed, Oct 27, 2010 at 01:52:58AM +0200, Ilya Yanok wrote: > Currently completed descriptors are processed in the tasklet. This can > lead to dead lock in case of CONFIG_NET_DMA enabled (new requests are > submitted from softirq context and dma_memcpy_to_iovec() busy loops until > the requests is submitted). To prevent this we should process completed > descriptors from the allocation failure path in prepare_memcpy too. > > Signed-off-by: Ilya Yanok <yanok@emcraft.com> > Cc: Piotr Ziecik <kosmo@semihalf.com> Merged for -next, thanks. g. > --- > drivers/dma/mpc512x_dma.c | 79 +++++++++++++++++++++++++------------------- > 1 files changed, 45 insertions(+), 34 deletions(-) > > diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c > index 97b92ec..59c2701 100644 > --- a/drivers/dma/mpc512x_dma.c > +++ b/drivers/dma/mpc512x_dma.c > @@ -328,19 +328,55 @@ static irqreturn_t mpc_dma_irq(int irq, void *data) > return IRQ_HANDLED; > } > > -/* DMA Tasklet */ > -static void mpc_dma_tasklet(unsigned long data) > +/* proccess completed descriptors */ > +static void mpc_dma_process_completed(struct mpc_dma *mdma) > { > - struct mpc_dma *mdma = (void *)data; > dma_cookie_t last_cookie = 0; > struct mpc_dma_chan *mchan; > struct mpc_dma_desc *mdesc; > struct dma_async_tx_descriptor *desc; > unsigned long flags; > LIST_HEAD(list); > - uint es; > int i; > > + for (i = 0; i < mdma->dma.chancnt; i++) { > + mchan = &mdma->channels[i]; > + > + /* Get all completed descriptors */ > + spin_lock_irqsave(&mchan->lock, flags); > + if (!list_empty(&mchan->completed)) > + list_splice_tail_init(&mchan->completed, &list); > + spin_unlock_irqrestore(&mchan->lock, flags); > + > + if (list_empty(&list)) > + continue; > + > + /* Execute callbacks and run dependencies */ > + list_for_each_entry(mdesc, &list, node) { > + desc = &mdesc->desc; > + > + if (desc->callback) > + desc->callback(desc->callback_param); > + > + last_cookie = desc->cookie; > + dma_run_dependencies(desc); > + } > + > + /* Free descriptors */ > + spin_lock_irqsave(&mchan->lock, flags); > + list_splice_tail_init(&list, &mchan->free); > + mchan->completed_cookie = last_cookie; > + spin_unlock_irqrestore(&mchan->lock, flags); > + } > +} > + > +/* DMA Tasklet */ > +static void mpc_dma_tasklet(unsigned long data) > +{ > + struct mpc_dma *mdma = (void *)data; > + unsigned long flags; > + uint es; > + > spin_lock_irqsave(&mdma->error_status_lock, flags); > es = mdma->error_status; > mdma->error_status = 0; > @@ -379,35 +415,7 @@ static void mpc_dma_tasklet(unsigned long data) > dev_err(mdma->dma.dev, "- Destination Bus Error\n"); > } > > - for (i = 0; i < mdma->dma.chancnt; i++) { > - mchan = &mdma->channels[i]; > - > - /* Get all completed descriptors */ > - spin_lock_irqsave(&mchan->lock, flags); > - if (!list_empty(&mchan->completed)) > - list_splice_tail_init(&mchan->completed, &list); > - spin_unlock_irqrestore(&mchan->lock, flags); > - > - if (list_empty(&list)) > - continue; > - > - /* Execute callbacks and run dependencies */ > - list_for_each_entry(mdesc, &list, node) { > - desc = &mdesc->desc; > - > - if (desc->callback) > - desc->callback(desc->callback_param); > - > - last_cookie = desc->cookie; > - dma_run_dependencies(desc); > - } > - > - /* Free descriptors */ > - spin_lock_irqsave(&mchan->lock, flags); > - list_splice_tail_init(&list, &mchan->free); > - mchan->completed_cookie = last_cookie; > - spin_unlock_irqrestore(&mchan->lock, flags); > - } > + mpc_dma_process_completed(mdma); > } > > /* Submit descriptor to hardware */ > @@ -587,8 +595,11 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src, > } > spin_unlock_irqrestore(&mchan->lock, iflags); > > - if (!mdesc) > + if (!mdesc) { > + /* try to free completed descriptors */ > + mpc_dma_process_completed(mdma); > return NULL; > + } > > mdesc->error = 0; > tcd = mdesc->tcd; > -- > 1.7.2.3 > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev
diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c index 97b92ec..59c2701 100644 --- a/drivers/dma/mpc512x_dma.c +++ b/drivers/dma/mpc512x_dma.c @@ -328,19 +328,55 @@ static irqreturn_t mpc_dma_irq(int irq, void *data) return IRQ_HANDLED; } -/* DMA Tasklet */ -static void mpc_dma_tasklet(unsigned long data) +/* proccess completed descriptors */ +static void mpc_dma_process_completed(struct mpc_dma *mdma) { - struct mpc_dma *mdma = (void *)data; dma_cookie_t last_cookie = 0; struct mpc_dma_chan *mchan; struct mpc_dma_desc *mdesc; struct dma_async_tx_descriptor *desc; unsigned long flags; LIST_HEAD(list); - uint es; int i; + for (i = 0; i < mdma->dma.chancnt; i++) { + mchan = &mdma->channels[i]; + + /* Get all completed descriptors */ + spin_lock_irqsave(&mchan->lock, flags); + if (!list_empty(&mchan->completed)) + list_splice_tail_init(&mchan->completed, &list); + spin_unlock_irqrestore(&mchan->lock, flags); + + if (list_empty(&list)) + continue; + + /* Execute callbacks and run dependencies */ + list_for_each_entry(mdesc, &list, node) { + desc = &mdesc->desc; + + if (desc->callback) + desc->callback(desc->callback_param); + + last_cookie = desc->cookie; + dma_run_dependencies(desc); + } + + /* Free descriptors */ + spin_lock_irqsave(&mchan->lock, flags); + list_splice_tail_init(&list, &mchan->free); + mchan->completed_cookie = last_cookie; + spin_unlock_irqrestore(&mchan->lock, flags); + } +} + +/* DMA Tasklet */ +static void mpc_dma_tasklet(unsigned long data) +{ + struct mpc_dma *mdma = (void *)data; + unsigned long flags; + uint es; + spin_lock_irqsave(&mdma->error_status_lock, flags); es = mdma->error_status; mdma->error_status = 0; @@ -379,35 +415,7 @@ static void mpc_dma_tasklet(unsigned long data) dev_err(mdma->dma.dev, "- Destination Bus Error\n"); } - for (i = 0; i < mdma->dma.chancnt; i++) { - mchan = &mdma->channels[i]; - - /* Get all completed descriptors */ - spin_lock_irqsave(&mchan->lock, flags); - if (!list_empty(&mchan->completed)) - list_splice_tail_init(&mchan->completed, &list); - spin_unlock_irqrestore(&mchan->lock, flags); - - if (list_empty(&list)) - continue; - - /* Execute callbacks and run dependencies */ - list_for_each_entry(mdesc, &list, node) { - desc = &mdesc->desc; - - if (desc->callback) - desc->callback(desc->callback_param); - - last_cookie = desc->cookie; - dma_run_dependencies(desc); - } - - /* Free descriptors */ - spin_lock_irqsave(&mchan->lock, flags); - list_splice_tail_init(&list, &mchan->free); - mchan->completed_cookie = last_cookie; - spin_unlock_irqrestore(&mchan->lock, flags); - } + mpc_dma_process_completed(mdma); } /* Submit descriptor to hardware */ @@ -587,8 +595,11 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src, } spin_unlock_irqrestore(&mchan->lock, iflags); - if (!mdesc) + if (!mdesc) { + /* try to free completed descriptors */ + mpc_dma_process_completed(mdma); return NULL; + } mdesc->error = 0; tcd = mdesc->tcd;
Currently completed descriptors are processed in the tasklet. This can lead to dead lock in case of CONFIG_NET_DMA enabled (new requests are submitted from softirq context and dma_memcpy_to_iovec() busy loops until the requests is submitted). To prevent this we should process completed descriptors from the allocation failure path in prepare_memcpy too. Signed-off-by: Ilya Yanok <yanok@emcraft.com> Cc: Piotr Ziecik <kosmo@semihalf.com> --- drivers/dma/mpc512x_dma.c | 79 +++++++++++++++++++++++++------------------- 1 files changed, 45 insertions(+), 34 deletions(-)