From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D1DFF1494D9 for ; Sun, 16 Nov 2025 05:47:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763272029; cv=none; b=Qq/YKHBiME/eCU08fLPUNAigeiBDXdrbWksd0UrZjuRMEcEZZOGjPfpsNflWl7kjOzTjOy695HPyQSZMlJWY9sRPNLcsxdsLjm2qGD6JCxohWODVG8b1sTckf1y0yUISmGY7TqZ7ys5SAfcwbXsvsTQkEMdMTN91awl0qx4cvAE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763272029; c=relaxed/simple; bh=VhOMKlmPNnj++jPAfsYIirLTiTxgnvzCapK9dNUeqh4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sHAuVcQMZ0o7nAqewWuMXm9PrYFk2DuBaFv3DtbapU1pPkHbRoUU8i0Q3eGP9UDFyIt1Y3r/JsUV58OiVaeo+gNh9VpPTJfSLP2jQ8Rqy3fymfsgRr5zbzFySF2/xL2sYh1iDR3ko71m6DVucymo6+GHEdNo9CBFcQPW2n3mo0M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f3PCgUrw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f3PCgUrw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76BC3C4CEF1; Sun, 16 Nov 2025 05:47:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763272024; bh=VhOMKlmPNnj++jPAfsYIirLTiTxgnvzCapK9dNUeqh4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f3PCgUrwougN1zKXC/ev3tHuCXsaagLLqRXl/9tu2Vy+Q5BYNo60sdkckcgpRRkRU QW4GB0Kd8l9K7CfxK6inwHkofGiAJW4FCHeX9iPcQVgo/2k1VUB/URuLhPJUhHeJMH XjA7bpDP3ojHGNPeh2+YxcLCr3gLbA6dhQUbSqLpXKPoR8yD9tLi8PcEySBcqGGArm 3AwRNFOA6U+wc6hui7nDl+xEkKE4EQKLe51hmRd2T41pI/OG+VIwz3wOT+ChDSUKpD Ze0N7ubs+fQL1k5c6JGtCaiVCWqdgSyrp78MXINMZtvweJweSkHQWElSAcwwUKdIY0 MZcJyLTcQl76Q== Date: Sun, 16 Nov 2025 07:46:56 +0200 From: Mike Rapoport To: Pasha Tatashin Cc: akpm@linux-foundation.org, bhe@redhat.com, jasonmiu@google.com, arnd@arndb.de, coxu@redhat.com, dave@vasilevsky.ca, ebiggers@google.com, graf@amazon.com, kees@kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH v2 10/13] kho: Update FDT dynamically for subtree addition/removal Message-ID: References: <20251114190002.3311679-1-pasha.tatashin@soleen.com> <20251114190002.3311679-11-pasha.tatashin@soleen.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Sat, Nov 15, 2025 at 09:51:07AM -0500, Pasha Tatashin wrote: > On Sat, Nov 15, 2025 at 4:40 AM Mike Rapoport wrote: > > > > On Fri, Nov 14, 2025 at 01:59:59PM -0500, Pasha Tatashin wrote: > > > - struct kho_sub_fdt *sub_fdt; > > > + phys_addr_t phys = virt_to_phys(fdt); > > > + void *root_fdt = kho_out.fdt; > > > + int err = -ENOMEM; > > > + int off, fdt_err; > > > > > > - sub_fdt = kmalloc(sizeof(*sub_fdt), GFP_KERNEL); > > > - if (!sub_fdt) > > > - return -ENOMEM; > > > + guard(mutex)(&kho_out.lock); > > > + > > > + fdt_err = fdt_open_into(root_fdt, root_fdt, PAGE_SIZE); > > > + if (fdt_err < 0) > > > + return err; > > > > > > - INIT_LIST_HEAD(&sub_fdt->l); > > > - sub_fdt->name = name; > > > - sub_fdt->fdt = fdt; > > > + off = fdt_add_subnode(root_fdt, 0, name); > > > > Why not > > fdt_err = fdt_add_subnode() > > > > as I asked in v1 review? > > > > Oh, I missed that, there is a slight difference between the two: > 'fdt_err' only contains FDT return value, i.e. error if negative. The > 'off' on the other hand in the happy path contains subnode offset, and > contains error only in the unhappy path. This is why I think it is a > little cleaner to keep different name, however, if you still prefer > re-using a single local variable for both, this is fix-up patch: > > diff --git a/kernel/liveupdate/kexec_handover.c > b/kernel/liveupdate/kexec_handover.c > index 224bdf5becb6..81f60ccb2dc7 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -713,7 +713,7 @@ int kho_add_subtree(const char *name, void *fdt) > phys_addr_t phys = virt_to_phys(fdt); > void *root_fdt = kho_out.fdt; > int err = -ENOMEM; > - int off, fdt_err; > + int fdt_err; > > guard(mutex)(&kho_out.lock); > > @@ -721,14 +721,14 @@ int kho_add_subtree(const char *name, void *fdt) > if (fdt_err < 0) > return err; > > - off = fdt_add_subnode(root_fdt, 0, name); > - if (off < 0) { > - if (off == -FDT_ERR_EXISTS) > + fdt_err = fdt_add_subnode(root_fdt, 0, name); > + if (fdt_err < 0) { > + if (fdt_err == -FDT_ERR_EXISTS) > err = -EEXIST; > goto out_pack; > } > > - err = fdt_setprop(root_fdt, off, PROP_SUB_FDT, &phys, sizeof(phys)); > + err = fdt_setprop(root_fdt, fdt_err, PROP_SUB_FDT, &phys, sizeof(phys)); I missed 'off' here, never mind > if (err < 0) > goto out_pack; > -- Sincerely yours, Mike.