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btl/vader: handle unexpected short read/write in process_vm_{read,wri… #4874

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Merged
merged 1 commit into from
Mar 5, 2018
Merged

btl/vader: handle unexpected short read/write in process_vm_{read,wri… #4874

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36 changes: 31 additions & 5 deletions opal/mca/btl/vader/btl_vader_get.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@
/*
* Copyright (c) 2010-2014 Los Alamos National Security, LLC. All rights
* reserved.
* Copyright (c) 2018 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
Expand All @@ -23,6 +25,7 @@
#include "opal/sys/cma.h"
#endif /* OPAL_CMA_NEED_SYSCALL_DEFS */


#endif

/**
Expand Down Expand Up @@ -71,11 +74,34 @@ int mca_btl_vader_get_cma (mca_btl_base_module_t *btl, mca_btl_base_endpoint_t *
struct iovec dst_iov = {.iov_base = local_address, .iov_len = size};
ssize_t ret;

ret = process_vm_readv (endpoint->segment_data.other.seg_ds->seg_cpid, &dst_iov, 1, &src_iov, 1, 0);
if (ret != (ssize_t)size) {
opal_output(0, "Read %ld, expected %lu, errno = %d\n", (long)ret, (unsigned long)size, errno);
return OPAL_ERROR;
}
/*
* According to the man page :
* "On success, process_vm_readv() returns the number of bytes read and
* process_vm_writev() returns the number of bytes written. This return
* value may be less than the total number of requested bytes, if a
* partial read/write occurred. (Partial transfers apply at the
* granularity of iovec elements. These system calls won't perform a
* partial transfer that splits a single iovec element.)".
* So since we use a single iovec element, the returned size should either
* be 0 or size, and the do loop should not be needed here.
* We tried on various Linux kernels with size > 2 GB, and surprisingly,
* the returned value is always 0x7ffff000 (fwiw, it happens to be the size
* of the larger number of pages that fits a signed 32 bits integer).
* We do not know whether this is a bug from the kernel, the libc or even
* the man page, but for the time being, we do as is process_vm_readv() could
* return any value.
*/
do {
ret = process_vm_readv (endpoint->segment_data.other.seg_ds->seg_cpid, &dst_iov, 1, &src_iov, 1, 0);
if (0 > ret) {
opal_output(0, "Read %ld, expected %lu, errno = %d\n", (long)ret, (unsigned long)size, errno);
return OPAL_ERROR;
}
src_iov.iov_base = (void *)((char *)src_iov.iov_base + ret);
src_iov.iov_len -= ret;
dst_iov.iov_base = (void *)((char *)dst_iov.iov_base + ret);
dst_iov.iov_len -= ret;
} while (0 < src_iov.iov_len);

/* always call the callback function */
cbfunc (btl, endpoint, local_address, local_handle, cbcontext, cbdata, OPAL_SUCCESS);
Expand Down
21 changes: 14 additions & 7 deletions opal/mca/btl/vader/btl_vader_put.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,8 @@
/*
* Copyright (c) 2010-2014 Los Alamos National Security, LLC. All rights
* reserved.
* Copyright (c) 2014 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* Copyright (c) 2014-2018 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
Expand Down Expand Up @@ -69,11 +69,18 @@ int mca_btl_vader_put_cma (mca_btl_base_module_t *btl, mca_btl_base_endpoint_t *
struct iovec dst_iov = {.iov_base = (void *)(intptr_t) remote_address, .iov_len = size};
ssize_t ret;

ret = process_vm_writev (endpoint->segment_data.other.seg_ds->seg_cpid, &src_iov, 1, &dst_iov, 1, 0);
if (ret != (ssize_t)size) {
opal_output(0, "Wrote %ld, expected %lu, errno = %d\n", (long)ret, (unsigned long)size, errno);
return OPAL_ERROR;
}
/* This should not be needed, see the rationale in mca_btl_vader_get_cma() */
do {
ret = process_vm_writev (endpoint->segment_data.other.seg_ds->seg_cpid, &src_iov, 1, &dst_iov, 1, 0);
if (0 > ret) {
opal_output(0, "Wrote %ld, expected %lu, errno = %d\n", (long)ret, (unsigned long)size, errno);
return OPAL_ERROR;
}
src_iov.iov_base = (void *)((char *)src_iov.iov_base + ret);
src_iov.iov_len -= ret;
dst_iov.iov_base = (void *)((char *)dst_iov.iov_base + ret);
dst_iov.iov_len -= ret;
} while (0 < src_iov.iov_len);

/* always call the callback function */
cbfunc (btl, endpoint, local_address, local_handle, cbcontext, cbdata, OPAL_SUCCESS);
Expand Down