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Fri, 14 Mar 2025 09:08:05 +0000 (GMT) Message-ID: <1263bf89-a2dd-4ae9-a8f9-9c36ddd08208@linux.ibm.com> Date: Fri, 14 Mar 2025 14:38:04 +0530 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/6] powerpc: fadump: use lock guard for mutex To: Peter Zijlstra Cc: maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com, christophe.leroy@csgroup.eu, mpe@ellerman.id.au, fbarrat@linux.ibm.com, ajd@linux.ibm.com, mahesh@linux.ibm.com, oohall@gmail.com, hbathini@linux.ibm.com, dhowells@redhat.com, haren@linux.ibm.com, linux-kernel@vger.kernel.org References: <20250314054544.1998928-1-sshegde@linux.ibm.com> <20250314054544.1998928-4-sshegde@linux.ibm.com> <20250314082223.GT5880@noisy.programming.kicks-ass.net> From: Shrikanth Hegde Content-Language: en-US In-Reply-To: <20250314082223.GT5880@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 2aHaGjGqb04H9xa5NdtJKF2BmYUQP55S X-Proofpoint-GUID: 5qlFFH1qpa3l-RY29U11zq59JxMJzqO4 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-14_03,2025-03-13_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1015 bulkscore=0 malwarescore=0 phishscore=0 mlxlogscore=744 mlxscore=0 impostorscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503140071 On 3/14/25 13:52, Peter Zijlstra wrote: Thanks Peter for taking a look. > On Fri, Mar 14, 2025 at 11:15:41AM +0530, Shrikanth Hegde wrote: >> use guard(mutex) for scope based resource management of mutex. >> This would make the code simpler and easier to maintain. >> >> More details on lock guards can be found at >> https://lore.kernel.org/all/20230612093537.614161713@infradead.org/T/#u >> >> Signed-off-by: Shrikanth Hegde >> --- >> arch/powerpc/kernel/fadump.c | 6 ++---- >> 1 file changed, 2 insertions(+), 4 deletions(-) >> >> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c >> index 4b371c738213..5fd2c546fd8c 100644 >> --- a/arch/powerpc/kernel/fadump.c >> +++ b/arch/powerpc/kernel/fadump.c >> @@ -1374,15 +1374,13 @@ static void fadump_free_elfcorehdr_buf(void) >> >> static void fadump_invalidate_release_mem(void) >> { >> - mutex_lock(&fadump_mutex); >> + guard(mutex)(&fadump_mutex); >> + >> if (!fw_dump.dump_active) { >> - mutex_unlock(&fadump_mutex); >> return; >> } >> >> fadump_cleanup(); >> - mutex_unlock(&fadump_mutex); >> - > > This will result in running the below functions with the mutex held. > >> fadump_free_elfcorehdr_buf(); >> fadump_release_memory(fw_dump.boot_mem_top, memblock_end_of_DRAM()); >> fadump_free_cpu_notes_buf(); > Ok. Got it, since the variable is still in scope unlock wont be called. So, will use scoped_guard as you suggested below in v2. > > The equivalent transformation for the above code would look like: > > static void fadump_invalidate_release_mem(void) > { > scoped_guard (mutex, &fadump_mutex) { > if (!fw_dump.dump_active) > return; > > fadump_cleanup(); > } > > fadump_free_elfcorehdr_buf(); > ... ok.