Re: [PATCH 00/61] treewide: Use IS_ERR_OR_NULL over manual NULL check - refactor
From: James Bottomley <James.Bottomley@HansenPartnership.com>
Date: 2026-03-12 15:32:41
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On Thu, 2026-03-12 at 09:57 -0300, Jason Gunthorpe wrote:
On Wed, Mar 11, 2026 at 02:40:36AM +0800, Kuan-Wei Chiu wrote:quoted
IMHO, the necessity of IS_ERR_OR_NULL() often highlights a confusing or flawed API design. It usually implies that the caller is unsure whether a failure results in an error pointer or a NULL pointer.+1 IS_ERR_OR_NULL() should always be looked on with suspicion. Very little should be returning some tri-state 'ERR' 'NULL' 'SUCCESS' pointer. What does the middle condition even mean? IS_ERR_OR_NULL() implies ERR and NULL are semanticly the same, so fix the things to always use ERR.
Not in any way supporting the original patch. However, the pattern ERR, NULL, PTR is used extensively in the dentry code of filesystems. See the try_lookup..() set of functions in fs/namei.c The meaning is PTR - I found it NULL - It definitely doesn't exist ERR - something went wrong during the lookup. So I don't think you can blanket say this pattern is wrong. Regards, James