Messages in this thread | | | Subject | Re: [PATCH] um: add a generic "fd" vector transport | From | Anton Ivanov <> | Date | Wed, 8 Apr 2020 19:10:15 +0100 |
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On 08/04/2020 18:07, Marc-André Lureau wrote: > Hi > > On Tue, Apr 7, 2020 at 11:02 PM Anton Ivanov > <anton.ivanov@cambridgegreys.com> wrote: >> >> On 07/04/2020 21:28, Marc-André Lureau wrote: >>> Learn to take a pre-opened file-descriptor for vector IO. >>> >>> Instead of teaching the driver to open a FD in multiple ways, it can >>> rely on management layer to do it on its behalf. For example, this >>> allows inheriting a preconfigured device fd or a simple socketpair() >>> setup, without further arguments, privileges or system access by UML. >>> >>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> >>> --- >>> arch/um/drivers/vector_user.c | 59 +++++++++++++++++++++++++++++++++++ >>> 1 file changed, 59 insertions(+) >>> >>> diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c >>> index 29fae0456ade..45c1550dbb37 100644 >>> --- a/arch/um/drivers/vector_user.c >>> +++ b/arch/um/drivers/vector_user.c >>> @@ -29,6 +29,7 @@ >>> #include <netdb.h> >>> #include <stdlib.h> >>> #include <os.h> >>> +#include <limits.h> >>> #include <um_malloc.h> >>> #include "vector_user.h" >>> >>> @@ -42,6 +43,9 @@ >>> #define TRANS_RAW "raw" >>> #define TRANS_RAW_LEN strlen(TRANS_RAW) >>> >>> +#define TRANS_FD "fd" >>> +#define TRANS_FD_LEN strlen(TRANS_FD) >>> + >>> #define VNET_HDR_FAIL "could not enable vnet headers on fd %d" >>> #define TUN_GET_F_FAIL "tapraw: TUNGETFEATURES failed: %s" >>> #define L2TPV3_BIND_FAIL "l2tpv3_open : could not bind socket err=%i" >>> @@ -347,6 +351,59 @@ static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id) >>> return NULL; >>> } >>> >>> +static int strtofd(const char *nptr) >>> +{ >>> + long fd; >>> + char *endptr; >>> + >>> + if (nptr == NULL) >>> + return -1; >>> + >>> + errno = 0; >>> + fd = strtol(nptr, &endptr, 10); >>> + if (nptr == endptr || >>> + errno != 0 || >>> + *endptr != '\0' || >>> + fd < 0 || >>> + fd > INT_MAX) { >>> + return -1; >>> + } >>> + return fd; >>> +} >>> + >>> +static struct vector_fds *user_init_fd_fds(struct arglist *ifspec) >>> +{ >>> + int fd = -1; >>> + char *fdarg = NULL; >>> + struct vector_fds *result = NULL; >>> + >>> + fdarg = uml_vector_fetch_arg(ifspec, "fd"); >>> + fd = strtofd(fdarg); >>> + if (fd == -1) { >>> + printk(UM_KERN_ERR "fd open: bad or missing fd argument"); >>> + goto fd_cleanup; >>> + } >>> + >>> + result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL); >>> + if (result == NULL) { >>> + printk(UM_KERN_ERR "fd open: allocation failed"); >>> + goto fd_cleanup; >>> + } >>> + >>> + result->rx_fd = fd; >>> + result->tx_fd = fd; >>> + result->remote_addr_size = 0; >>> + result->remote_addr = NULL; >>> + return result; >>> + >>> +fd_cleanup: >>> + if (fd >= 0) >>> + os_close_file(fd); >>> + if (result != NULL) >>> + kfree(result); >>> + return NULL; >>> +} >>> + >>> static struct vector_fds *user_init_raw_fds(struct arglist *ifspec) >>> { >>> int rxfd = -1, txfd = -1; >>> @@ -578,6 +635,8 @@ struct vector_fds *uml_vector_user_open( >>> return user_init_socket_fds(parsed, ID_L2TPV3); >>> if (strncmp(transport, TRANS_BESS, TRANS_BESS_LEN) == 0) >>> return user_init_unix_fds(parsed, ID_BESS); >>> + if (strncmp(transport, TRANS_FD, TRANS_FD_LEN) == 0) >>> + return user_init_fd_fds(parsed); >>> return NULL; >>> } >>> >>> >> >> We should also control enable/disable of recv/sendmmsg as an option here. >> >> It can be made generic and be fed into get_transport_options() in >> vector_kern.c as an override. > > So actually, there seems to be a way to do that already: > > vec0:transport=fd,fd=N,vec=0
I have forgotten about it (it's been a while since I wrote the drivers).
I will update the docs.
In that case the patch looks good to go, I will ack it shortly.
> >> >> -- >> Anton R. Ivanov >> Cambridgegreys Limited. Registered in England. Company Number 10273661 >> https://www.cambridgegreys.com/ >> > >
-- Anton R. Ivanov Cambridgegreys Limited. Registered in England. Company Number 10273661 https://www.cambridgegreys.com/
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