register_netdev() race with ip addr
I am developing a proof of concept for a networking application that uses a generic stack interface driver that connects the stack to a userspace application rather than a physical device. This driver works fine and is in production.
The problem I have encountered is this: after I register the device in the kernel module for that driver via register_netdev(), I must sleep between 3ms and 6ms before I can successfully call "ip addr add". It would obviously be better to query something to see if I can set the IP address than to wait for a fixed time (or repeatedly attempt to set it until it sticks).
I am running 4.19.19 with Centos 7.6.
Does anyone know how to check (in a C application, via a system call, via sysfs, etc) if a network device is ready to receive an IP address? Here are some things I have tried without success (they return before I can successfully set the IP without sleeping):
1) Waiting for net_device.flags & IFF_UP
2) Waiting for net_device.reg_state == NETREG_REGISTERED
3) Waiting for netif_running(net_device)
I have also waited to see that I have an index reported by ioctl(fd, SIOCGIFINDEX...), and I seem to right after registering the device.
It feels like something in the network registration notify chain is taking its sweet time to finish up, but I have no idea what it is or how to tell when it is done.
linux kernel
migrated from stackoverflow.com 10 mins ago
This question came from our site for professional and enthusiast programmers.
add a comment |
I am developing a proof of concept for a networking application that uses a generic stack interface driver that connects the stack to a userspace application rather than a physical device. This driver works fine and is in production.
The problem I have encountered is this: after I register the device in the kernel module for that driver via register_netdev(), I must sleep between 3ms and 6ms before I can successfully call "ip addr add". It would obviously be better to query something to see if I can set the IP address than to wait for a fixed time (or repeatedly attempt to set it until it sticks).
I am running 4.19.19 with Centos 7.6.
Does anyone know how to check (in a C application, via a system call, via sysfs, etc) if a network device is ready to receive an IP address? Here are some things I have tried without success (they return before I can successfully set the IP without sleeping):
1) Waiting for net_device.flags & IFF_UP
2) Waiting for net_device.reg_state == NETREG_REGISTERED
3) Waiting for netif_running(net_device)
I have also waited to see that I have an index reported by ioctl(fd, SIOCGIFINDEX...), and I seem to right after registering the device.
It feels like something in the network registration notify chain is taking its sweet time to finish up, but I have no idea what it is or how to tell when it is done.
linux kernel
migrated from stackoverflow.com 10 mins ago
This question came from our site for professional and enthusiast programmers.
add a comment |
I am developing a proof of concept for a networking application that uses a generic stack interface driver that connects the stack to a userspace application rather than a physical device. This driver works fine and is in production.
The problem I have encountered is this: after I register the device in the kernel module for that driver via register_netdev(), I must sleep between 3ms and 6ms before I can successfully call "ip addr add". It would obviously be better to query something to see if I can set the IP address than to wait for a fixed time (or repeatedly attempt to set it until it sticks).
I am running 4.19.19 with Centos 7.6.
Does anyone know how to check (in a C application, via a system call, via sysfs, etc) if a network device is ready to receive an IP address? Here are some things I have tried without success (they return before I can successfully set the IP without sleeping):
1) Waiting for net_device.flags & IFF_UP
2) Waiting for net_device.reg_state == NETREG_REGISTERED
3) Waiting for netif_running(net_device)
I have also waited to see that I have an index reported by ioctl(fd, SIOCGIFINDEX...), and I seem to right after registering the device.
It feels like something in the network registration notify chain is taking its sweet time to finish up, but I have no idea what it is or how to tell when it is done.
linux kernel
I am developing a proof of concept for a networking application that uses a generic stack interface driver that connects the stack to a userspace application rather than a physical device. This driver works fine and is in production.
The problem I have encountered is this: after I register the device in the kernel module for that driver via register_netdev(), I must sleep between 3ms and 6ms before I can successfully call "ip addr add". It would obviously be better to query something to see if I can set the IP address than to wait for a fixed time (or repeatedly attempt to set it until it sticks).
I am running 4.19.19 with Centos 7.6.
Does anyone know how to check (in a C application, via a system call, via sysfs, etc) if a network device is ready to receive an IP address? Here are some things I have tried without success (they return before I can successfully set the IP without sleeping):
1) Waiting for net_device.flags & IFF_UP
2) Waiting for net_device.reg_state == NETREG_REGISTERED
3) Waiting for netif_running(net_device)
I have also waited to see that I have an index reported by ioctl(fd, SIOCGIFINDEX...), and I seem to right after registering the device.
It feels like something in the network registration notify chain is taking its sweet time to finish up, but I have no idea what it is or how to tell when it is done.
linux kernel
linux kernel
asked Mar 7 at 22:55
Jeremy Whatley
migrated from stackoverflow.com 10 mins ago
This question came from our site for professional and enthusiast programmers.
migrated from stackoverflow.com 10 mins ago
This question came from our site for professional and enthusiast programmers.
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