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Mon, 19 Jul 2021 13:53:44 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D4921AE059; Mon, 19 Jul 2021 13:53:43 +0000 (GMT) Received: from localhost.localdomain (unknown [9.145.62.205]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 19 Jul 2021 13:53:43 +0000 (GMT) Subject: Re: [PATCH v5 02/11] powerpc/kernel/iommu: Add new iommu_table_in_use() helper To: Leonardo Bras , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Alexey Kardashevskiy , David Gibson , kernel test robot , Nicolin Chen Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20210716082755.428187-1-leobras.c@gmail.com> <20210716082755.428187-3-leobras.c@gmail.com> From: Frederic Barrat Message-ID: <29c199f3-63a8-3edb-b29e-de157431d89f@linux.ibm.com> Date: Mon, 19 Jul 2021 15:53:43 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210716082755.428187-3-leobras.c@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: TFluKUD2HZvcl5_ntqKYotqIH5VodY1O X-Proofpoint-GUID: RfAfaSxtRfVXmhLnVoCkiQZccTmjhGoO X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-07-19_05:2021-07-19,2021-07-19 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 clxscore=1015 bulkscore=0 spamscore=0 mlxscore=0 lowpriorityscore=0 malwarescore=0 mlxlogscore=999 priorityscore=1501 phishscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2107190078 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/07/2021 10:27, Leonardo Bras wrote: > @@ -1099,18 +1105,13 @@ int iommu_take_ownership(struct iommu_table *tbl) > for (i = 0; i < tbl->nr_pools; i++) > spin_lock_nest_lock(&tbl->pools[i].lock, &tbl->large_pool.lock); > > - iommu_table_release_pages(tbl); > - > - if (!bitmap_empty(tbl->it_map, tbl->it_size)) { > + if (iommu_table_in_use(tbl)) { > pr_err("iommu_tce: it_map is not empty"); > ret = -EBUSY; > - /* Undo iommu_table_release_pages, i.e. restore bit#0, etc */ > - iommu_table_reserve_pages(tbl, tbl->it_reserved_start, > - tbl->it_reserved_end); > - } else { > - memset(tbl->it_map, 0xff, sz); > } > > + memset(tbl->it_map, 0xff, sz); > + So if the table is not empty, we fail (EBUSY) but we now also completely overwrite the bitmap. It was in an unexpected state, but we're making it worse. Or am I missing something? Fred > for (i = 0; i < tbl->nr_pools; i++) > spin_unlock(&tbl->pools[i].lock); > spin_unlock_irqrestore(&tbl->large_pool.lock, flags);