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[24.6.192.50]) by smtp.gmail.com with ESMTPSA id h88-v6sm25968932pfa.184.2018.10.15.13.16.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Oct 2018 13:16:51 -0700 (PDT) Subject: Re: [PATCH v3 09/18] of: overlay: validate overlay properties #address-cells and #size-cells To: Alan Tull Cc: Rob Herring , Pantelis Antoniou , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Moritz Fischer , linux-kernel , linuxppc-dev , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-fpga@vger.kernel.org References: <1539563070-12969-1-git-send-email-frowand.list@gmail.com> <1539563070-12969-10-git-send-email-frowand.list@gmail.com> From: Frank Rowand Message-ID: <87525c4a-6c7d-5c1d-1f99-6784f315b89c@gmail.com> Date: Mon, 15 Oct 2018 13:16:50 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/15/18 12:01, Alan Tull wrote: > On Sun, Oct 14, 2018 at 7:26 PM wrote: >> >> From: Frank Rowand >> >> If overlay properties #address-cells or #size-cells are already in >> the live devicetree for any given node, then the values in the >> overlay must match the values in the live tree. >> >> If the properties are already in the live tree then there is no >> need to create a changeset entry to add them since they must >> have the same value. This reduces the memory used by the >> changeset and eliminates a possible memory leak. This is >> verified by 12 fewer warnings during the devicetree unittest, >> as the possible memory leak warnings about #address-cells and >> >> Signed-off-by: Frank Rowand >> --- >> drivers/of/overlay.c | 38 +++++++++++++++++++++++++++++++++++--- >> 1 file changed, 35 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c >> index 272a0d1a5e18..ee66651db553 100644 >> --- a/drivers/of/overlay.c >> +++ b/drivers/of/overlay.c >> @@ -287,7 +287,12 @@ static struct property *dup_and_fixup_symbol_prop( >> * @target may be either in the live devicetree or in a new subtree that >> * is contained in the changeset. >> * >> - * Some special properties are not updated (no error returned). >> + * Some special properties are not added or updated (no error returned): >> + * "name", "phandle", "linux,phandle". >> + * >> + * Properties "#address-cells" and "#size-cells" are not updated if they >> + * are already in the live tree, but if present in the live tree, the values >> + * in the overlay must match the values in the live tree. >> * >> * Update of property in symbols node is not allowed. >> * >> @@ -300,6 +305,7 @@ static int add_changeset_property(struct overlay_changeset *ovcs, >> { >> struct property *new_prop = NULL, *prop; >> int ret = 0; >> + bool check_for_non_overlay_node = false; >> >> if (!of_prop_cmp(overlay_prop->name, "name") || >> !of_prop_cmp(overlay_prop->name, "phandle") || >> @@ -322,13 +328,39 @@ static int add_changeset_property(struct overlay_changeset *ovcs, >> if (!new_prop) >> return -ENOMEM; >> >> - if (!prop) >> + if (!prop) { >> + >> + check_for_non_overlay_node = true; >> ret = of_changeset_add_property(&ovcs->cset, target->np, >> new_prop); >> - else >> + >> + } else if (!of_prop_cmp(prop->name, "#address-cells")) { >> + > > Hi Frank, > > If we get these ERROR messages, I suggest that this function should > return an error so the overlay will be rejected. > >> + if (prop->length != 4 || new_prop->length != 4 || >> + *(u32 *)prop->value != *(u32 *)new_prop->value) > > *(u32 *)prop->value != *(u32 *)new_prop->value) { > >> + pr_err("ERROR: overlay and/or live tree #address-cells invalid in node %pOF\n", >> + target->np); > > ret = -EINVAL; > } > > Otherwise there is an ERROR message, but it continues trying to apply > the invalid overlay anyway and I get an oops. By adding the ret = > -EINVAL, the overlay gets rejected and the oops is avoided. Yes, that sounds good. >> + >> + } else if (!of_prop_cmp(prop->name, "#size-cells")) { >> + >> + if (prop->length != 4 || new_prop->length != 4 || >> + *(u32 *)prop->value != *(u32 *)new_prop->value) >> + pr_err("ERROR: overlay and/or live tree #size-cells invalid in node %pOF\n", >> + target->np); > > Add the ret = -EINVAL here also. This give me the following (if my > overlay changes #address-cells): Yes. > [ 21.167551] OF: overlay: ERROR: overlay and/or live tree > #address-cells invalid in node /soc/base_fpga_region > [ 21.177442] OF: overlay: add_changeset_property ret=-22 > [ 21.182656] create_overlay: Failed to create overlay (err=-22) > > Also, I wonder if the ERROR message could be more direct. Currently > it says the #address-cells property is invalid but that doesn't say > anything about why it's invalid. How about something like: > > OF: overlay: ERROR: changing #address-cells not allowed (/soc/base_fpga_region) That sounds like a more useful message, maybe a slight change s/changing #address-cells/changing value of #address-cells/ > The 'OF: overlay' part still makes it clear it's overlay related. The > rest of it makes it clear *why* it's invalid. This ERROR will be a > surprise for people who have been using overlays, so that could be > helpful to light the way a bit. > > Alan > >> + >> + } else { >> + >> + check_for_non_overlay_node = true; >> ret = of_changeset_update_property(&ovcs->cset, target->np, >> new_prop); >> >> + } >> + >> + if (check_for_non_overlay_node && >> + !of_node_check_flag(target->np, OF_OVERLAY)) >> + pr_err("WARNING: %s(), memory leak will occur if overlay removed. Property: %pOF/%s\n", >> + __func__, target->np, new_prop->name); >> + >> if (ret) { >> kfree(new_prop->name); >> kfree(new_prop->value); >> -- >> Frank Rowand >> >