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SubjectRe: [2.6 patch][2/3] kernel/ BUG -> BUG_ON conversions
Date
On Aug 28, 2004, at 11:17, Adrian Bunk wrote:
> The patch below does BUG -> BUG_ON conversions in kernel/ .
>
> --- linux-2.6.9-rc1-mm1-full-3.4/kernel/cpu.c.old 2004-08-28
> 16:05:17.000000000 +0200
> +++ linux-2.6.9-rc1-mm1-full-3.4/kernel/cpu.c 2004-08-28
> 16:06:24.000000000 +0200
> @@ -156,9 +156,8 @@
> kthread_bind(p, smp_processor_id());
>
> /* CPU is completely dead: tell everyone. Too late to complain. */
> - if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
> - == NOTIFY_BAD)
> - BUG();
> + BUG_ON(notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
> + == NOTIFY_BAD);

Can't do this, without DEBUG the notifier_call_chain _won't_ be executed

> check_for_tasks(cpu);
>
> @@ -203,8 +202,7 @@
> ret = __cpu_up(cpu);
> if (ret != 0)
> goto out_notify;
> - if (!cpu_online(cpu))
> - BUG();
> + BUG_ON(!cpu_online(cpu));

Does cpu_online() have any side effects?

>
> /* Now call notifier in preparation. */
> notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
> --- linux-2.6.9-rc1-mm1-full-3.4/kernel/exit.c.old 2004-08-28
> 16:05:17.000000000 +0200
> +++ linux-2.6.9-rc1-mm1-full-3.4/kernel/exit.c 2004-08-28
> 16:08:24.000000000 +0200
> @@ -503,7 +503,7 @@
> down_read(&mm->mmap_sem);
> }
> atomic_inc(&mm->mm_count);
> - if (mm != tsk->active_mm) BUG();
> + BUG_ON(mm != tsk->active_mm);
> /* more a memory barrier than a real lock */
> task_lock(tsk);
> tsk->mm = NULL;
> @@ -878,11 +877,9 @@
> const struct list_head *tmp, *head = &link->pidptr->task_list;
>
> #ifdef CONFIG_SMP
> - if (!p->sighand)
> - BUG();
> - if (!spin_is_locked(&p->sighand->siglock) &&
> - !rwlock_is_locked(&tasklist_lock))
> - BUG();
> + BUG_ON(!p->sighand);
> + BUG_ON(!spin_is_locked(&p->sighand->siglock) &&
> + !rwlock_is_locked(&tasklist_lock));

These _should_ be OK, but I'm not sure if spin_is_locked and
rwlock_is_locked
have any memory barrier guarantees.

> #endif
> tmp = link->pid_chain.next;
> if (tmp == head)
> @@ -1350,8 +1347,7 @@
> if (options & __WNOTHREAD)
> break;
> tsk = next_thread(tsk);
> - if (tsk->signal != current->signal)
> - BUG();
> + BUG_ON(tsk->signal != current->signal);
> } while (tsk != current);
>
> read_unlock(&tasklist_lock);
> --- linux-2.6.9-rc1-mm1-full-3.4/kernel/fork.c.old 2004-08-28
> 16:05:17.000000000 +0200
> +++ linux-2.6.9-rc1-mm1-full-3.4/kernel/fork.c 2004-08-28
> 16:08:45.000000000 +0200
> @@ -809,8 +809,7 @@
> struct files_struct *files = current->files;
> int rc;
>
> - if(!files)
> - BUG();
> + BUG_ON(!files);
>
> /* This can race but the race causes us to copy when we don't
> need to and drop the copy */
> --- linux-2.6.9-rc1-mm1-full-3.4/kernel/module.c.old 2004-08-28
> 16:05:17.000000000 +0200
> +++ linux-2.6.9-rc1-mm1-full-3.4/kernel/module.c 2004-08-28
> 16:13:44.000000000 +0200
> @@ -655,8 +655,7 @@
> const unsigned long *crc;
>
> spin_lock_irqsave(&modlist_lock, flags);
> - if (!__find_symbol(symbol, &owner, &crc, 1))
> - BUG();
> + BUG_ON(!__find_symbol(symbol, &owner, &crc, 1));

Does __find_symbol have side effects?

> module_put(owner);
> spin_unlock_irqrestore(&modlist_lock, flags);
> }
> @@ -667,8 +666,7 @@
> unsigned long flags;
>
> spin_lock_irqsave(&modlist_lock, flags);
> - if (!kernel_text_address((unsigned long)addr))
> - BUG();
> + BUG_ON(!kernel_text_address((unsigned long)addr));

Side effects?

> module_put(module_text_address((unsigned long)addr));
> spin_unlock_irqrestore(&modlist_lock, flags);
> @@ -905,8 +903,7 @@
> const unsigned long *crc;
> struct module *owner;
>
> - if (!__find_symbol("struct_module", &owner, &crc, 1))
> - BUG();
> + BUG_ON(!__find_symbol("struct_module", &owner, &crc, 1));
> return check_version(sechdrs, versindex, "struct_module", mod,
> crc);
> }

[Bunch of patch chomped]

Please verify that you don't pull important function calls into
BUG_ON() statements.

Cheers,
Kyle Moffett

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