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Use a single, consistent approach to returning success versus failure in

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vm_map_madvise().  Previously, vm_map_madvise() used a traditional Unix-
style "return (0);" to indicate success in the common case, but Mach-
style return values in the edge cases.  Since KERN_SUCCESS equals zero,
the only problem with this inconsistency was stylistic.  vm_map_madvise()
has exactly two callers in the entire source tree, and only one of them
cares about the return value.  That caller, kern_madvise(), can be
simplified if vm_map_madvise() consistently uses Unix-style return
values.

Since vm_map_madvise() uses the variable modify_map as a Boolean, make it
one.

Eliminate a redundant error check from kern_madvise().  Add a comment
explaining where the check is performed.

Explicitly note that exec_release_args_kva() doesn't care about
vm_map_madvise()'s return value.  Since MADV_FREE is passed as the
behavior, the return value will always be zero.

Reviewed by:	kib, markj
MFC after:	7 days
This commit is contained in:
Alan Cox 2018-06-04 16:28:06 +00:00
parent a8db1fa14d
commit 3e7cb27cdd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=334621
3 changed files with 11 additions and 14 deletions
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2
sys/kern/kern_exec.c
View File

@ -1380,7 +1380,7 @@ exec_release_args_kva(struct exec_args_kva *argkva, u_int gen)
base = argkva->addr;
if (argkva->gen != gen) {
vm_map_madvise(exec_map, base, base + exec_map_entry_size,
(void)vm_map_madvise(exec_map, base, base + exec_map_entry_size,
MADV_FREE);
argkva->gen = gen;
}

11
sys/vm/vm_map.c
View File

@ -2215,7 +2215,7 @@ vm_map_madvise(
int behav)
{
vm_map_entry_t current, entry;
int modify_map = 0;
bool modify_map;
/*
* Some madvise calls directly modify the vm_map_entry, in which case
@ -2232,19 +2232,20 @@ vm_map_madvise(
case MADV_NOCORE:
case MADV_CORE:
if (start == end)
return (KERN_SUCCESS);
modify_map = 1;
return (0);
modify_map = true;
vm_map_lock(map);
break;
case MADV_WILLNEED:
case MADV_DONTNEED:
case MADV_FREE:
if (start == end)
return (KERN_SUCCESS);
return (0);
modify_map = false;
vm_map_lock_read(map);
break;
default:
return (KERN_INVALID_ARGUMENT);
return (EINVAL);
}
/*

12
sys/vm/vm_mmap.c
View File

@ -682,11 +682,6 @@ kern_madvise(struct thread *td, uintptr_t addr0, size_t len, int behav)
PROC_SPROTECT, &flags));
}
/*
* Check for illegal behavior
*/
if (behav < 0 || behav > MADV_CORE)
return (EINVAL);
/*
* Check for illegal addresses. Watch out for address wrap... Note
* that VM_*_ADDRESS are not constants due to casts (argh).
@ -705,9 +700,10 @@ kern_madvise(struct thread *td, uintptr_t addr0, size_t len, int behav)
start = trunc_page(addr);
end = round_page(addr + len);
if (vm_map_madvise(map, start, end, behav))
return (EINVAL);
return (0);
/*
* vm_map_madvise() checks for illegal values of behav.
*/
return (vm_map_madvise(map, start, end, behav));
}
#ifndef _SYS_SYSPROTO_H_