[fault] Generalise NETDEV_DISCARD_RATE fault injection mechanism

Provide a generic inject_fault() function that can be used to inject
random faults with configurable probabilities.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/config/fault.h b/src/config/fault.h
new file mode 100644 (file)
index 0000000..a05aecd
--- /dev/null
+++ b/src/config/fault.h
@@ -0,0 +1,19 @@
+#ifndef CONFIG_FAULT_H
+#define CONFIG_FAULT_H
+
+/** @file
+ *
+ * Fault injection
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <config/defaults.h>
+
+/* Drop every N transmitted or received network packets */
+#define        NETDEV_DISCARD_RATE 0
+
+#include <config/local/fault.h>
+
+#endif /* CONFIG_FAULT_H */

diff --git a/src/config/general.h b/src/config/general.h
index 9a5fbca9538c3e8578c88c16ccece166b621aaa6..35a9030eccb228e18aa930a6be757cc5ff1cab8f 100644 (file)
--- a/src/config/general.h
+++ b/src/config/general.h
@@ -156,7 +156,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  *
  */
 
-#define        NETDEV_DISCARD_RATE 0   /* Drop every N packets (0=>no drop) */
 #undef BUILD_SERIAL            /* Include an automatic build serial
                                 * number.  Add "bs" to the list of
                                 * make targets.  For example:

diff --git a/src/core/fault.c b/src/core/fault.c
new file mode 100644 (file)
index 0000000..91289fd
--- /dev/null
+++ b/src/core/fault.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdlib.h>
+#include <errno.h>
+#include <ipxe/fault.h>
+
+/** @file
+ *
+ * Fault injection
+ *
+ */
+
+/**
+ * Inject fault with a specified probability
+ *
+ * @v rate             Reciprocal of fault probability (must be non-zero)
+ * @ret rc             Return status code
+ */
+int inject_fault_nonzero ( unsigned int rate ) {
+
+       /* Do nothing unless we want to inject a fault now */
+       if ( ( random() % rate ) != 0 )
+               return 0;
+
+       /* Generate error number here so that faults can be injected
+        * into files that don't themselves have error file
+        * identifiers (via errfile.h).
+        */
+       return -EFAULT;
+}

diff --git a/src/include/ipxe/errfile.h b/src/include/ipxe/errfile.h
index b665f4909885445e444ab86fc87a42f5e19efce8..6553cd8758b668c471d7ddf33815a31adb618c99 100644 (file)
--- a/src/include/ipxe/errfile.h
+++ b/src/include/ipxe/errfile.h
@@ -68,6 +68,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define ERRFILE_fbcon                 ( ERRFILE_CORE | 0x001c0000 )
 #define ERRFILE_ansicol                       ( ERRFILE_CORE | 0x001d0000 )
 #define ERRFILE_ansicoldef            ( ERRFILE_CORE | 0x001e0000 )
+#define ERRFILE_fault                 ( ERRFILE_CORE | 0x001f0000 )
 
 #define ERRFILE_eisa                ( ERRFILE_DRIVER | 0x00000000 )
 #define ERRFILE_isa                 ( ERRFILE_DRIVER | 0x00010000 )

diff --git a/src/include/ipxe/fault.h b/src/include/ipxe/fault.h
new file mode 100644 (file)
index 0000000..32aa064
--- /dev/null
+++ b/src/include/ipxe/fault.h
@@ -0,0 +1,32 @@
+#ifndef _IPXE_FAULT_H
+#define _IPXE_FAULT_H
+
+/** @file
+ *
+ * Fault injection
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <config/fault.h>
+
+extern int inject_fault_nonzero ( unsigned int rate );
+
+/**
+ * Inject fault with a specified probability
+ *
+ * @v rate             Reciprocal of fault probability (zero for no faults)
+ * @ret rc             Return status code
+ */
+static inline __attribute__ (( always_inline )) int
+inject_fault ( unsigned int rate ) {
+
+       /* Force dead code elimination in non-fault-injecting builds */
+       if ( rate == 0 )
+               return 0;
+
+       return inject_fault_nonzero ( rate );
+}
+
+#endif /* _IPXE_FAULT_H */

diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index f2821efe1ca2f7c08bf05adbd3ef711f51035bc6..889b00c1a471f048335d7c365ea41b1a6e8ab6d9 100644 (file)
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -39,6 +39,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/device.h>
 #include <ipxe/errortab.h>
 #include <ipxe/profile.h>
+#include <ipxe/fault.h>
 #include <ipxe/vlan.h>
 #include <ipxe/netdevice.h>
 
@@ -303,11 +304,8 @@ int netdev_tx ( struct net_device *netdev, struct io_buffer *iobuf ) {
        }
 
        /* Discard packet (for test purposes) if applicable */
-       if ( ( NETDEV_DISCARD_RATE > 0 ) &&
-            ( ( random() % NETDEV_DISCARD_RATE ) == 0 ) ) {
-               rc = -EAGAIN;
+       if ( ( rc = inject_fault ( NETDEV_DISCARD_RATE ) ) != 0 )
                goto err;
-       }
 
        /* Transmit packet */
        if ( ( rc = netdev->op->transmit ( netdev, iobuf ) ) != 0 )
@@ -457,14 +455,14 @@ static void netdev_tx_flush ( struct net_device *netdev ) {
  * function takes ownership of the I/O buffer.
  */
 void netdev_rx ( struct net_device *netdev, struct io_buffer *iobuf ) {
+       int rc;
 
        DBGC2 ( netdev, "NETDEV %s received %p (%p+%zx)\n",
                netdev->name, iobuf, iobuf->data, iob_len ( iobuf ) );
 
        /* Discard packet (for test purposes) if applicable */
-       if ( ( NETDEV_DISCARD_RATE > 0 ) &&
-            ( ( random() % NETDEV_DISCARD_RATE ) == 0 ) ) {
-               netdev_rx_err ( netdev, iobuf, -EAGAIN );
+       if ( ( rc = inject_fault ( NETDEV_DISCARD_RATE ) ) != 0 ) {
+               netdev_rx_err ( netdev, iobuf, rc );
                return;
        }