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From: Mimi Zohar To: =?UTF-8?Q?=E6=9D=8E=E5=8A=9B=E7=90=BC?= , THOBY Simon Cc: "dmitry.kasatkin@gmail.com" , "jmorris@namei.org" , "serge@hallyn.com" , "linux-integrity@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-kernel@vger.kernel.org" Date: Mon, 23 Aug 2021 07:22:52 -0400 In-Reply-To: References: <20210819101529.28001-1-liqiong@nfschina.com> <8d17f252-4a93-f430-3f25-e75556ab01e8@viveris.fr> <1f631c3d-5dce-e477-bfb3-05aa38836442@viveris.fr> <96037695de6125c701889c168550def278adfd4b.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-16.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: g2p-jfAEwP1_o5IHdxq3PZExC3W0pgL0 X-Proofpoint-GUID: KMYptE5LDttQ0Zun41GftQCmHs3n4MpA X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-23_02:2021-08-23,2021-08-23 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 clxscore=1015 phishscore=0 mlxscore=0 malwarescore=0 bulkscore=0 spamscore=0 impostorscore=0 mlxlogscore=999 lowpriorityscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108230074 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Liqiong, On Mon, 2021-08-23 at 11:04 +0800, 李力琼 wrote: > Hi Mimi : > > The situation is a little different,'list_splice_init_rcu' > don't change the list head. If "ima_rules" being changed, > readers may can't reload the new value in time for cpu cache > or compiler optimization. Defining "ima_rules" as a volatile > variable can fix, but It is inefficient. After looking at list_splice_tail_init_rcu() some more, it is actually making sure there aren't any readers traversing "ima_temp_rules", not "ima_policy_rules". There aren't any readers traversing "ima_temp_rules". > > Maybe using a temporary ima_rules variable for every > "list_for_each_entry_rcu(entry, ima_rules, list)" loop is > a better solution to fix the "endless loop" bug. Agreed thanks, Mimi