Fix divide by zero error in calculate_num_nodes_up_to_level using MPI_Bcast with 2 tasks #11120
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with MPI_Bcast in 2 tasks using --mca coll_adapt_bcast_algorithm 6 and --mca coll_adapt_priority 99 Resolve review comments Signed-off-by: David Wootton <[email protected]> (cherry picked from commit a74927f)
jjhursey
approved these changes
Nov 28, 2022
bosilca
approved these changes
Nov 28, 2022
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Clang static analysis reported a possible zerodivide exception at ompi/mca/coll/base/coll_base_topo.c:62 (calculate_num_nodes_up_to_level)
I was able to get this exception with the program
#include <mpi.h>
char buff[4096];
int main(int argc, char *argv[]) {
MPI_Init(&argc, &argv);
MPI_Bcast(buff, sizeof buff, MPI_CHAR, 0, MPI_COMM_WORLD);
MPI_Finalize();
}
Using the command
mpirun -n 2 --mca coll_adapt_bcast_algorithm 6 --mca coll_adapt_priority 99 bcast
The calculate_num_nodes_up_to_level function is called from ompi_coll_base_topo_build_tree. The exception occurs because fanout is set to one in this case.
This is a cherry pick of #11103 from the main branch
Signed-off-by: David Wootton [email protected]
(cherry picked from commit a74927f)