[PATCH v2] ioat_alloc_chan_resources should not perform sleeping allocations.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On a kernel with DEBUG_LOCKS, ioat_free_chan_resources triggers an
in_interrupt() warning.  With PROVE_LOCKING, it reports detecting a
SOFTIRQ-safe to SOFTIRQ-unsafe lock ordering in the same code path.

This is because dma_generic_alloc_coherent() checks if the GFP flags
permit blocking.  It allocates from different subsystems if blocking is
permitted.  The free path knows how to return the memory to the correct
allocator.  If GFP_KERNEL is specified then the alloc and free end up
going through cma_alloc(), which uses mutexes.

Given that ioat_free_chan_resources() can be called in interrupt
context, ioat_alloc_chan_resources() must specify GFP_NOWAIT so that the
allocations do not block and instead use an allocator that uses
spinlocks.

Signed-off-by: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
---
 drivers/dma/ioat/init.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
index 90eddd9..823cdb9 100644
--- a/drivers/dma/ioat/init.c
+++ b/drivers/dma/ioat/init.c
@@ -693,7 +693,7 @@ static int ioat_alloc_chan_resources(struct dma_chan *c)
 	/* doing 2 32bit writes to mmio since 1 64b write doesn't work */
 	ioat_chan->completion =
 		dma_pool_zalloc(ioat_chan->ioat_dma->completion_pool,
-				GFP_KERNEL, &ioat_chan->completion_dma);
+				GFP_NOWAIT, &ioat_chan->completion_dma);
 	if (!ioat_chan->completion)
 		return -ENOMEM;
 
@@ -703,7 +703,7 @@ static int ioat_alloc_chan_resources(struct dma_chan *c)
 	       ioat_chan->reg_base + IOAT_CHANCMP_OFFSET_HIGH);
 
 	order = IOAT_MAX_ORDER;
-	ring = ioat_alloc_ring(c, order, GFP_KERNEL);
+	ring = ioat_alloc_ring(c, order, GFP_NOWAIT);
 	if (!ring)
 		return -ENOMEM;
 
-- 
2.7.4
--
To unsubscribe from this list: send the line "unsubscribe dmaengine" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Kernel]     [Linux ARM (vger)]     [Linux ARM MSM]     [Linux Omap]     [Linux Arm]     [Linux Tegra]     [Fedora ARM]     [Linux for Samsung SOC]     [eCos]     [Linux PCI]     [Linux Fastboot]     [Gcc Help]     [Git]     [DCCP]     [IETF Announce]     [Security]     [Linux MIPS]     [Yosemite Campsites]

  Powered by Linux