[netsniff-ng] [PATCH] trafgen: fix packet socket initialization with multiple CPUs

[Paolo Abeni]

The commit 78c13b71e196 ("trafgen: Allow to generate packets
to output pcap file") introduced a regression when output is
a network device and multiple CPU are in use: the packet
socket is created before fork() and thus the socket is shared
among all the processes: all of them except the first will
fail while setting the tx_ring.

Fix it splitting the io open() helper in a create() op,
called before forking, and the open() op called by each process.

Fixes: 78c13b71e196 ("trafgen: Allow to generate packets to output pcap file")
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
 trafgen.c     |  6 ++++--
 trafgen_dev.c | 21 +++++++++++++--------
 trafgen_dev.h |  4 +++-
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/trafgen.c b/trafgen.c
index 9b54399..9c5a9a6 100644
--- a/trafgen.c
+++ b/trafgen.c
@@ -977,6 +977,7 @@ static void main_loop(struct ctx *ctx, char *confname, bool 
slow,
                fflush(stdout);
        }
 
+       dev_io_open(ctx->dev_out);
        if (dev_io_is_netdev(ctx->dev_out) && ctx->qdisc_path == false)
                set_sock_qdisc_bypass(dev_io_fd_get(ctx->dev_out), 
ctx->verbose);
 
@@ -1266,12 +1267,13 @@ int main(int argc, char **argv)
        xlockme();
 
        if (ctx.pcap_in) {
-               ctx.dev_in = dev_io_open(ctx.pcap_in, DEV_IO_IN);
+               ctx.dev_in = dev_io_create(ctx.pcap_in, DEV_IO_IN);
                if (!ctx.dev_in)
                        panic("Failed to open input device\n");
+               dev_io_open(ctx.dev_in);
        }
 
-       ctx.dev_out = dev_io_open(ctx.device, DEV_IO_OUT);
+       ctx.dev_out = dev_io_create(ctx.device, DEV_IO_OUT);
        if (!ctx.dev_out)
                panic("Failed to open output device\n");
 
diff --git a/trafgen_dev.c b/trafgen_dev.c
index f65442f..489da98 100644
--- a/trafgen_dev.c
+++ b/trafgen_dev.c
@@ -242,10 +242,11 @@ static const struct dev_io_ops dev_cfg_ops = {
        .close = dev_cfg_close,
 };
 
-struct dev_io *dev_io_open(const char *name, enum dev_io_mode_t mode)
+struct dev_io *dev_io_create(const char *name, enum dev_io_mode_t mode)
 {
        struct dev_io *dev = xzmalloc(sizeof(struct dev_io));
 
+       dev->mode = mode;
        if (strstr(name, ".pcap")) {
                dev->name = xstrdup(name);
                dev->ops = &dev_pcap_ops;
@@ -260,16 +261,20 @@ struct dev_io *dev_io_open(const char *name, enum 
dev_io_mode_t mode)
                return NULL;
        }
 
-       if (dev->ops->open) {
-               if (dev->ops->open(dev, name, mode)) {
-                       xfree(dev);
-                       return NULL;
-               }
-       }
-
        return dev;
 };
 
+extern void dev_io_open(struct dev_io *dev)
+{
+       bug_on(!dev);
+       bug_on(!dev->ops);
+
+       if (dev->ops->open)
+               if (dev->ops->open(dev, dev->name, dev->mode))
+                       panic("Cannot open io %s mode %d\n", dev->name,
+                             dev->mode);
+}
+
 int dev_io_write(struct dev_io *dev, struct packet *pkt)
 {
        bug_on(!dev);
diff --git a/trafgen_dev.h b/trafgen_dev.h
index 80086d7..bcb88f3 100644
--- a/trafgen_dev.h
+++ b/trafgen_dev.h
@@ -24,6 +24,7 @@ struct dev_io {
        uint32_t pcap_magic;
        bool is_initialized;
        enum pcap_mode pcap_mode;
+       enum dev_io_mode_t mode;
        size_t buf_len;
        uint8_t *buf;
 
@@ -39,7 +40,8 @@ struct dev_io_ops {
        void(*close) (struct dev_io *dev);
 };
 
-extern struct dev_io *dev_io_open(const char *name, enum dev_io_mode_t mode);
+extern struct dev_io *dev_io_create(const char *name, enum dev_io_mode_t mode);
+extern void dev_io_open(struct dev_io *dev);
 extern int dev_io_write(struct dev_io *dev, struct packet *pkt);
 extern struct packet *dev_io_read(struct dev_io *dev);
 extern int dev_io_ifindex_get(struct dev_io *dev);
-- 
2.13.5

-- 
You received this message because you are subscribed to the Google Groups 
"netsniff-ng" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to netsniff-ng+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.