Documentation: add SCSI drivers' mapping error handling to DMA-API-HOWTO
Add the concrete DMA mapping error handling for SCSI drivers on the
queuecommand path.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index 93d9087..a38ddad 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -745,6 +745,10 @@
(ndo_start_xmit). This means that the socket buffer is just dropped in
the failure case.
+SCSI drivers must return SCSI_MLQUEUE_HOST_BUSY if the DMA mapping
+fails in the queuecommand hook. This means that the SCSI subsystem
+passes the command to the driver again later.
+
Closing
This document, and the API itself, would not be in its current