From: Ira Snyder Date: Thu, 26 Jan 2012 11:00:14 +0000 (+0000) Subject: carma-fpga: fix race between data dumping and DMA callback X-Git-Tag: v3.4-rc1~159^2~46 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6c15d7afbb2f9e2d3114b513306dae736b56f535;p=pandora-kernel.git carma-fpga: fix race between data dumping and DMA callback When the system is under heavy load, we occasionally saw a problem where the system would get a legitimate interrupt when they should be disabled. This was caused by the data_dma_cb() DMA callback unconditionally re-enabling FPGA interrupts even when data dumping is disabled. When data dumping was re-enabled, the irq handler would fire while a DMA was in progress. The "BUG_ON(priv->inflight != NULL);" during the second invocation of the DMA callback caused the system to crash. To fix the issue, the priv->enabled boolean is moved under the protection of the priv->lock spinlock. The DMA callback checks the boolean to know whether to re-enable FPGA interrupts before it returns. Now that it is fixed, the driver keeps FPGA interrupts disabled when it expects that they are disabled, fixing the bug. Signed-off-by: Ira W. Snyder Cc: Benjamin Herrenschmidt Signed-off-by: Benjamin Herrenschmidt --- Reading git-diff-tree failed