Messages in this thread | | | From | Arnd Bergmann <> | Date | Wed, 6 Oct 2021 09:59:59 +0200 | Subject | Re: [PATCH] vsock: Handle compat 32-bit timeout |
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On Wed, Oct 6, 2021 at 9:48 AM Richard Palethorpe <rpalethorpe@suse.com> wrote: > > Allow 32-bit timevals to be used with a 64-bit kernel. > > This allows the LTP regression test vsock01 to run without > modification in 32-bit compat mode. > > Fixes: fe0c72f3db11 ("socket: move compat timeout handling into sock.c") > Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com> > > --- > > This is one of those fixes where I am not sure if we should just > change the test instead. Because it's not clear if someone is likely > to use vsock's in 32-bit compat mode?
We try very hard to ensure that compat mode works for every interface, so it should be fixed in the kernel. Running compat mode is common on memory-restricted machines, e.g. on cloud platforms and on deeply embedded systems.
However, I think fixing the SO_VM_SOCKETS_CONNECT_TIMEOUT to support 64-bit timeouts would actually be more important here. I think what you need to do is to define the macro the same way as the SO_TIMESTAMP one:
#define SO_RCVTIMEO (sizeof(time_t) == sizeof(__kernel_long_t) ? \ SO_RCVTIMEO_OLD : SO_RCVTIMEO_NEW) #define SO_TIMESTAMP (sizeof(time_t) == sizeof(__kernel_long_t) ? \ SO_TIMESTAMP_OLD : SO_TIMESTAMP_NEW) ...
to ensure that user space picks an interface that matches the user space definition of 'struct timeval'.
Your change looks correct otherwise, but I think you should first add the new interface for 64-bit timeouts, since that likely changes the code in a way that makes your current patch no longer the best way to write it.
Arnd
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