From: "Ira W. Snyder" Subject: Re: [PATCH v5 5/6] fsl-dma: use spin_lock_bh to instead of spin_lock_irqsave Date: Wed, 1 Aug 2012 10:30:59 -0700 Message-ID: <20120801173059.GF11359@ovro.caltech.edu> References: <1343811009-25466-1-git-send-email-qiang.liu@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, dan.j.williams@gmail.com, Vinod Koul , Timur Tabi , herbert@gondor.hengli.com.au, Dan Williams , davem@davemloft.net To: qiang.liu@freescale.com Return-path: Received: from ovro.ovro.caltech.edu ([192.100.16.2]:36144 "EHLO ovro.ovro.caltech.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753236Ab2HARbD (ORCPT ); Wed, 1 Aug 2012 13:31:03 -0400 Content-Disposition: inline In-Reply-To: <1343811009-25466-1-git-send-email-qiang.liu@freescale.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Wed, Aug 01, 2012 at 04:50:09PM +0800, qiang.liu@freescale.com wrote: > From: Qiang Liu > > - use spin_lock_bh() is the right way to use async_tx api, > dma_run_dependencies() should not be protected by spin_lock_irqsave(); > - use spin_lock_bh to instead of spin_lock_irqsave for improving performance, > There is not any place to access descriptor queues in fsl-dma ISR except its > tasklet, spin_lock_bh() is more proper here. Interrupts will be turned off and > context will be save in irqsave, there is needless to use irqsave.. > This description is not very clear English. I understand it is not your native language. Let me try to help. """ The use of spin_lock_irqsave() is a stronger locking mechanism than is required throughout the driver. The minimum locking required should be used instead. Change all instances of spin_lock_irqsave() to spin_lock_bh(). All manipulation of protected fields is done using tasklet context or weaker, which makes spin_lock_bh() the correct choice. """ Other than that, Acked-by: Ira W. Snyder > Cc: Dan Williams > Cc: Vinod Koul > Cc: Li Yang > Cc: Timur Tabi > Signed-off-by: Qiang Liu > --- > drivers/dma/fsldma.c | 30 ++++++++++++------------------ > 1 files changed, 12 insertions(+), 18 deletions(-) > > diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c > index bb883c0..e3814aa 100644 > --- a/drivers/dma/fsldma.c > +++ b/drivers/dma/fsldma.c > @@ -645,10 +645,9 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) > struct fsldma_chan *chan = to_fsl_chan(tx->chan); > struct fsl_desc_sw *desc = tx_to_fsl_desc(tx); > struct fsl_desc_sw *child; > - unsigned long flags; > dma_cookie_t cookie; > > - spin_lock_irqsave(&chan->desc_lock, flags); > + spin_lock_bh(&chan->desc_lock); > > /* > * assign cookies to all of the software descriptors > @@ -661,7 +660,7 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) > /* put this transaction onto the tail of the pending queue */ > append_ld_queue(chan, desc); > > - spin_unlock_irqrestore(&chan->desc_lock, flags); > + spin_unlock_bh(&chan->desc_lock); > > return cookie; > } > @@ -770,15 +769,14 @@ static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan, > static void fsl_dma_free_chan_resources(struct dma_chan *dchan) > { > struct fsldma_chan *chan = to_fsl_chan(dchan); > - unsigned long flags; > > chan_dbg(chan, "free all channel resources\n"); > - spin_lock_irqsave(&chan->desc_lock, flags); > + spin_lock_bh(&chan->desc_lock); > fsldma_cleanup_descriptor(chan); > fsldma_free_desc_list(chan, &chan->ld_pending); > fsldma_free_desc_list(chan, &chan->ld_running); > fsldma_free_desc_list(chan, &chan->ld_completed); > - spin_unlock_irqrestore(&chan->desc_lock, flags); > + spin_unlock_bh(&chan->desc_lock); > > dma_pool_destroy(chan->desc_pool); > chan->desc_pool = NULL; > @@ -997,7 +995,6 @@ static int fsl_dma_device_control(struct dma_chan *dchan, > { > struct dma_slave_config *config; > struct fsldma_chan *chan; > - unsigned long flags; > int size; > > if (!dchan) > @@ -1007,7 +1004,7 @@ static int fsl_dma_device_control(struct dma_chan *dchan, > > switch (cmd) { > case DMA_TERMINATE_ALL: > - spin_lock_irqsave(&chan->desc_lock, flags); > + spin_lock_bh(&chan->desc_lock); > > /* Halt the DMA engine */ > dma_halt(chan); > @@ -1017,7 +1014,7 @@ static int fsl_dma_device_control(struct dma_chan *dchan, > fsldma_free_desc_list(chan, &chan->ld_running); > chan->idle = true; > > - spin_unlock_irqrestore(&chan->desc_lock, flags); > + spin_unlock_bh(&chan->desc_lock); > return 0; > > case DMA_SLAVE_CONFIG: > @@ -1059,11 +1056,10 @@ static int fsl_dma_device_control(struct dma_chan *dchan, > static void fsl_dma_memcpy_issue_pending(struct dma_chan *dchan) > { > struct fsldma_chan *chan = to_fsl_chan(dchan); > - unsigned long flags; > > - spin_lock_irqsave(&chan->desc_lock, flags); > + spin_lock_bh(&chan->desc_lock); > fsl_chan_xfer_ld_queue(chan); > - spin_unlock_irqrestore(&chan->desc_lock, flags); > + spin_unlock_bh(&chan->desc_lock); > } > > /** > @@ -1076,15 +1072,14 @@ static enum dma_status fsl_tx_status(struct dma_chan *dchan, > { > struct fsldma_chan *chan = to_fsl_chan(dchan); > enum dma_status ret; > - unsigned long flags; > > ret = dma_cookie_status(dchan, cookie, txstate); > if (ret == DMA_SUCCESS) > return ret; > > - spin_lock_irqsave(&chan->desc_lock, flags); > + spin_lock_bh(&chan->desc_lock); > fsldma_cleanup_descriptor(chan); > - spin_unlock_irqrestore(&chan->desc_lock, flags); > + spin_unlock_bh(&chan->desc_lock); > > return dma_cookie_status(dchan, cookie, txstate); > } > @@ -1163,11 +1158,10 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data) > static void dma_do_tasklet(unsigned long data) > { > struct fsldma_chan *chan = (struct fsldma_chan *)data; > - unsigned long flags; > > chan_dbg(chan, "tasklet entry\n"); > > - spin_lock_irqsave(&chan->desc_lock, flags); > + spin_lock_bh(&chan->desc_lock); > > /* the hardware is now idle and ready for more */ > chan->idle = true; > @@ -1175,7 +1169,7 @@ static void dma_do_tasklet(unsigned long data) > /* Run all cleanup for this descriptor */ > fsldma_cleanup_descriptor(chan); > > - spin_unlock_irqrestore(&chan->desc_lock, flags); > + spin_unlock_bh(&chan->desc_lock); > > chan_dbg(chan, "tasklet exit\n"); > } > -- > 1.7.5.1 > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev