On Fri, 2021-10-29 at 19:35 +0200, Krzysztof Kozlowski wrote: > On 28/10/2021 07:50, Yong Wu wrote: > > We add the ostd setting for mt8195. It introduces a abort for the > > previous SoC which doesn't have ostd setting. This is the log: > > > > Unable to handle kernel NULL pointer dereference at virtual address > > 0000000000000080 > > ... > > pc : mtk_smi_larb_config_port_gen2_general+0x64/0x130 > > lr : mtk_smi_larb_resume+0x54/0x98 > > ... > > Call trace: > > mtk_smi_larb_config_port_gen2_general+0x64/0x130 > > pm_generic_runtime_resume+0x2c/0x48 > > __genpd_runtime_resume+0x30/0xa8 > > genpd_runtime_resume+0x94/0x2c8 > > __rpm_callback+0x44/0x150 > > rpm_callback+0x6c/0x78 > > rpm_resume+0x310/0x558 > > __pm_runtime_resume+0x3c/0x88 > > > > In the code: larbostd = larb->larb_gen->ostd[larb->larbid], > > if "larb->larb_gen->ostd" is null, the "larbostd" is the offset, it > > is > > also a valid value, thus, use the larb->larb_gen->ostd as the > > condition > > inside the "for" loop. > > You need to write more clearly, what you are fixing here. > > > > > Signed-off-by: Yong Wu <yong...@mediatek.com> > > --- > > Hi Krzysztof, > > Could you help review and conside this as a fix for the mt8195 > > patchset? > > The mt8195 patchset are not in mainline, thus, I don't know its > > sha-id, > > and don't add Fixes tag. > > Thanks > > --- > > drivers/memory/mtk-smi.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c > > index b883dcc0bbfa..0262a59a2d6e 100644 > > --- a/drivers/memory/mtk-smi.c > > +++ b/drivers/memory/mtk-smi.c > > @@ -257,7 +257,7 @@ static void > > mtk_smi_larb_config_port_gen2_general(struct device *dev) > > if (MTK_SMI_CAPS(flags_general, MTK_SMI_FLAG_SW_FLAG)) > > writel_relaxed(SMI_LARB_SW_FLAG_1, larb->base + > > SMI_LARB_SW_FLAG); > > > > - for (i = 0; i < SMI_LARB_PORT_NR_MAX && larbostd && > > !!larbostd[i]; i++) > > + for (i = 0; i < SMI_LARB_PORT_NR_MAX && larb->larb_gen->ostd && > > !!larbostd[i]; i++) > > writel_relaxed(larbostd[i], larb->base + > > SMI_LARB_OSTDL_PORTx(i)); > > The code does not look good. You have already a dereference at line > 244: > > const u8 *larbostd = larb->larb_gen->ostd[larb->larbid];
if larb->larb_gen->ostd is null, larbostd is the offset, e.g. 0x80 in the log above. thus, we can not use "larbostd[i]" in the "for" loop. sorry for the unreadable. In this case, is the change ok? or like this: -const u8 *larbostd = larb->larb_gen->ostd[larb->larbid]; +const u8 *larbostd = larb->larb_gen->ostd ? larb->larb_gen-ostd[larb- >larbid] : NULL; or add a explicit "if": if (larb->larb_gen->ostd) larbostd = xxx. Which one do you prefer? Thanks. > > You are not fixing the NULL pointer dereference. > > > > > for_each_set_bit(i, (unsigned long *)larb->mmu, 32) { > > > > > Best regards, > Krzysztof _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu