dChan
Anonymous ID: eff0e7 Dec. 12, 2018, 3:30 p.m. No.4279961   🗄️.is 🔗kun   >>0008

>>4279848

>>4279917

 

What does this code do?:

 

struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; struct group_info groups_alloc(int gidsetsize){ struct group_info group_info; int nblocks; int i; nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; / Make sure we always allocate at least one indirect block pointer / nblocks = nblocks ? : 1; group_info = kmalloc(sizeof(group_info) + nblockssizeof(gid_t ), GFP_USER); if (!group_info) return NULL; group_info->ngroups = gidsetsize; group_info->nblocks = nblocks; atomic_set(&group_info->usage, 1); if (gidsetsize <= NGROUPS_SMALL) group_info->blocks[0] = group_info->small_block; else { for (i = 0; i < nblocks; i++) { gid_t b; b = (void )__get_free_page(GFP_USER); if (!b) goto out_undo_partial_alloc; group_info->blocks[i] = b; } } return group_info; out_undo_partial_alloc: while (–i >= 0) { free_page((unsigned long)group_info->blocks[i]); } kfree(group_info); return NULL; } EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info group_info) { if (group_info->blocks[0] != group_info->small_block) { int i; for (i = 0; i < group_info->nblocks; i++) struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; struct group_info groups_alloc(int gidsetsize){ struct group_info group_info; int nblocks; int i; nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; / Make sure we always allocate at least one indirect block pointer / nblocks = nblocks ? : 1; group_info = kmalloc(sizeof(group_info) + nblockssizeof(gid_t ), GFP_USER); if (!group_info) return NULL; group_info->ngroups = gidsetsize; group_info->nblocks = nblocks; atomic_set(&group_info->usage, 1); if (gidsetsize <= NGROUPS_SMALL) group_info->blocks[0] = group_info->small_block; else { for (i = 0; i < nblocks; i++) { gid_t b; b = (void )__get_free_page(GFP_USER); if (!b) goto out_undo_partial_alloc; group_info->blocks[i] = b; } } return group_info; out_undo_partial_alloc: while (–i >= 0) { free_page((unsigned long)group_info->blocks[i]); } kfree(group_info); return NULL; } EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info group_info) { if (group_info->blocks[0] != group_info->small_block) { int i; for (i = 0; i < group_info->nblocks; i++) struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; struct group_info groups_alloc(int gidsetsize){ struct group_info group_info; int nblocks; int i; nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; / Make sure we always allocate at least one indirect block pointer / nblocks = nblocks ? : 1; group_info = kmalloc(sizeof(group_info) + nblockssizeof(gid_t ), GFP_USER); if (!group_info) return NULL; group_info->ngroups = gidsetsize; group_info->nblocks = nblocks; atomic_set(&group_info->usage, 1); if (gidsetsize <= NGROUPS_SMALL) group_info->blocks[0] = group_info->small_block; else { for (i = 0; i < nblocks; i++) { gid_t b; b = (void )__get_free_page(GFP_USER); if (!b) goto out_undo_partial_alloc; group_info->blocks[i] = b; } } return group_info; out_undo_partial_alloc: while (–i >= 0) { free_page((unsigned long)group_info->blocks[i]); } kfree(group_info); return NULL; } EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info group_info) { if (group_info->blocks[0] != group_info->small_block) { int i; for (i = 0; i < group_info->nblocks; i++) echo('BO SHUTDOWN');