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[63.128.21.74]) by gmr-mx.google.com with ESMTPS id s63si733670pjb.0.2020.03.29.18.04.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 29 Mar 2020 18:04:21 -0700 (PDT) Received-SPF: pass (google.com: domain of sbrivio@redhat.com designates 63.128.21.74 as permitted sender) client-ip=63.128.21.74; Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=gkn5t6Fp; spf=pass (google.com: domain of sbrivio@redhat.com designates 63.128.21.74 as permitted sender) smtp.mailfrom=sbrivio@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585530260; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=I9vvlWwS1mzV/l9P9r+QmimacGyJ01ArO1EoOE3YvtY=; b=gkn5t6Fpm04tvK5qip/6cpJto1Ohms5Ct1fUuNo8+625iOrzOj4FRxFh5aB7Wmw419btN+ U6AiHPywMwaLJAhmLw2EmUwomELtel8a0XMqbBzuDZOcZdkkyor2hEJwsZbd5jijmlU3Cq iJXyU7dJBpS433MAKUEgl03zjMLrwog= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-198-H3kFJQQXNQODNt_pAc7n6w-1; Sun, 29 Mar 2020 21:04:18 -0400 X-MC-Unique: H3kFJQQXNQODNt_pAc7n6w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9BF7F107ACC9; Mon, 30 Mar 2020 01:04:17 +0000 (UTC) Received: from elisabeth (unknown [10.40.208.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3B2A319925; Mon, 30 Mar 2020 01:04:15 +0000 (UTC) Date: Mon, 30 Mar 2020 03:04:11 +0200 From: Stefano Brivio To: Sam Muhammed Cc: Greg Kroah-Hartman , outreachy-kernel@googlegroups.com Subject: Re: [Outreachy kernel] [PATCH v2 1/7] Staging: kpc2000: kpc_dma: Remove comparison to NULL. Message-ID: <20200330030346.6420ddc6@elisabeth> In-Reply-To: References: Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 25 Mar 2020 10:26:36 -0400 Sam Muhammed wrote: > Comparison to NULL been used across the driver, > remove them and use (!var) instead. > > Checkpatch.pl: CHECK: > Comparison to NULL could be written "!desc"... etc > > Signed-off-by: Sam Muhammed > --- > Changes in v2: > - None. > > drivers/staging/kpc2000/kpc_dma/dma.c | 2 +- > drivers/staging/kpc2000/kpc_dma/fileops.c | 12 ++++++------ > drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.h | 4 ++-- > 3 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/staging/kpc2000/kpc_dma/dma.c b/drivers/staging/kpc2000/kpc_dma/dma.c > index 51a4dd534a0d..4bfbc717bc07 100644 > --- a/drivers/staging/kpc2000/kpc_dma/dma.c > +++ b/drivers/staging/kpc2000/kpc_dma/dma.c > @@ -236,7 +236,7 @@ int count_descriptors_available(struct kpc_dma_device *eng) > struct kpc_dma_descriptor *cur = eng->desc_next; > > while (cur != eng->desc_completed) { > - BUG_ON(cur == NULL); > + BUG_ON(!cur); > count++; > cur = cur->Next; > } > diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c > index 40525540dde6..5eb6c5f24feb 100644 > --- a/drivers/staging/kpc2000/kpc_dma/fileops.c > +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c > @@ -124,7 +124,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv, > pcnt = count_parts_for_sge(sg); > for (p = 0 ; p < pcnt ; p++) { > // Fill out the descriptor > - BUG_ON(desc == NULL); > + BUG_ON(!desc); > clear_desc(desc); > if (p != pcnt-1) { > desc->DescByteCount = 0x80000; > @@ -203,11 +203,11 @@ void transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags) > { > unsigned int i; > > - BUG_ON(acd == NULL); > - BUG_ON(acd->user_pages == NULL); > - BUG_ON(acd->sgt.sgl == NULL); > - BUG_ON(acd->ldev == NULL); > - BUG_ON(acd->ldev->pldev == NULL); > + BUG_ON(!acd); > + BUG_ON(!acd->user_pages); > + BUG_ON(!acd->sgt.sgl); > + BUG_ON(!acd->ldev); > + BUG_ON(!acd->ldev->pldev); I've seen some tool reporting this (perhaps Coccinelle?): with x == NULL, BUG_ON(!x) causes a kernel panic just like dereferencing x. So the first statement in e.g.: BUG_ON(!acd); BUG_ON(!acd->user_pages); is redundant. This change wouldn't be related to this patch, though. -- Stefano