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Thu, 7 May 2026 04:15:54 +0000 (GMT) Message-ID: Date: Thu, 7 May 2026 09:45:53 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] powerpc/fadump: Add timeout to RTAS busy-wait loops To: Adriano Vero , maddy@linux.ibm.com, mpe@ellerman.id.au Cc: npiggin@gmail.com, chleroy@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20260419065039.23495-1-adri.vero.dev@gmail.com> <20260506222024.30352-1-adri.vero.dev@gmail.com> Content-Language: en-US From: Sourabh Jain In-Reply-To: <20260506222024.30352-1-adri.vero.dev@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: Ho0tM30KDKkwUpsgHa5Hr2MX9wnHY-4K X-Proofpoint-GUID: NimJqW55oNkagq6F5PYdkq-Juda9dKbp X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA3MDAzNyBTYWx0ZWRfX0Xv4gQIJHsqY IkMUZkEM387ZlItyXd25CC04CO/e0pe9/dQrK0/v/s2jlpI5VznX//6jnQypviavtO8PQtk7k0L 0W7CRggMRsUVcpMRsKTcM5FKTKvap3VjX6SrTRI55V4e8fp89ONKoS2wpJv7+oUO3kfjD/A4uqW titXpiOL+kElBbSOidNcxaH+qeVGaA17+gLea8/6v4HM2ChDU6kjNzpN4Mfhy3WSSXUKpz6wcWk ongWCmVTa2KySsQWLZnUQq08CUfN860uO1q3NyC8r2esBFhE28cPjDyBu9X6J6/Et4hQ9lKHTZ7 ueMtxr/5mQKHaOnyuBUwdhIQfn0rBAu+e8mL3r7V+nnVrRE8p5wfERPx+zWxeiBPsY9/IjYU7B0 y/PHMjpaiNB8FXiG4vOwOyo1deLHaTsNWR+vhv8de4IyxHM9urmFaS8O0wPBs5xeS0cUbK0G73g 17jlJ0PSSic/plSsGqw== X-Authority-Analysis: v=2.4 cv=UbFhjqSN c=1 sm=1 tr=0 ts=69fc1200 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=ntDPK0L32HZQNU6beJgA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-06_02,2026-05-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 adultscore=0 priorityscore=1501 bulkscore=0 phishscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605070037 Hello Adriano, On 07/05/26 03:50, Adriano Vero wrote: > The ibm,configure-kernel-dump RTAS call sites in > rtas_fadump_register(), rtas_fadump_unregister(), and > rtas_fadump_invalidate() polled indefinitely while firmware returned > a busy status. A misbehaving or hung firmware could stall these paths > forever, blocking fadump registration at boot or preventing clean > teardown. > > Introduce rtas_fadump_call(), a helper that wraps the common > busy-wait pattern shared by all three sites. The helper accumulates > the total delay and returns -ETIMEDOUT if firmware keeps returning a > busy status beyond RTAS_FADUMP_MAX_WAIT_MS (60 seconds). A pr_debug() > message is emitted on each busy iteration to aid diagnosis when the > timeout is hit. > > Signed-off-by: Adriano Vero > > Reviewed-by: Sourabh Jain New line between tags is unnecessary. Including a Changelog in subsequent versions of the same patch is helpful for the maintainer and reviewers to understand what has changed in this version compared to the previous version. For example: https://lore.kernel.org/all/20260407124349.1698552-1-sourabhjain@linux.ibm.com/ Thanks, Sourabh Jain > --- > arch/powerpc/platforms/pseries/rtas-fadump.c | 80 ++++++++++++-------- > arch/powerpc/platforms/pseries/rtas-fadump.h | 6 ++ > 2 files changed, 53 insertions(+), 33 deletions(-) > > diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c > index eceb3289383e..3bb4ac2ab6cc 100644 > --- a/arch/powerpc/platforms/pseries/rtas-fadump.c > +++ b/arch/powerpc/platforms/pseries/rtas-fadump.c > @@ -179,9 +179,42 @@ static u64 rtas_fadump_get_bootmem_min(void) > return RTAS_FADUMP_MIN_BOOT_MEM; > } > > +/* > + * Helper to make an ibm,configure-kernel-dump RTAS call with a bounded > + * busy-wait loop. Returns the RTAS return code on completion, or > + * -ETIMEDOUT if firmware keeps returning a busy status beyond > + * RTAS_FADUMP_MAX_WAIT_MS milliseconds. > + */ > +static int rtas_fadump_call(struct fw_dump *fadump_conf, int operation, > + void *fdm_ptr, unsigned int fdm_size, > + const char *op_name) > +{ > + unsigned int wait_time, total_wait = 0; > + int rc; > + > + do { > + rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1, > + NULL, operation, fdm_ptr, fdm_size); > + wait_time = rtas_busy_delay_time(rc); > + if (wait_time) { > + pr_debug("Firmware busy during fadump %s, waiting %ums (total %ums)\n", > + op_name, wait_time, total_wait); > + if (total_wait >= RTAS_FADUMP_MAX_WAIT_MS) { > + pr_err("Timed out waiting for firmware to complete fadump %s\n", > + op_name); > + return -ETIMEDOUT; > + } > + total_wait += wait_time; > + mdelay(wait_time); > + } > + } while (wait_time); > + > + return rc; > +} > + > static int rtas_fadump_register(struct fw_dump *fadump_conf) > { > - unsigned int wait_time, fdm_size; > + unsigned int fdm_size; > int rc, err = -EIO; > > /* > @@ -192,16 +225,10 @@ static int rtas_fadump_register(struct fw_dump *fadump_conf) > fdm_size = sizeof(struct rtas_fadump_section_header); > fdm_size += be16_to_cpu(fdm.header.dump_num_sections) * sizeof(struct rtas_fadump_section); > > - /* TODO: Add upper time limit for the delay */ > - do { > - rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1, > - NULL, FADUMP_REGISTER, &fdm, fdm_size); > - > - wait_time = rtas_busy_delay_time(rc); > - if (wait_time) > - mdelay(wait_time); > - > - } while (wait_time); > + rc = rtas_fadump_call(fadump_conf, FADUMP_REGISTER, &fdm, fdm_size, > + "register"); > + if (rc == -ETIMEDOUT) > + return -ETIMEDOUT; > > switch (rc) { > case 0: > @@ -234,19 +261,12 @@ static int rtas_fadump_register(struct fw_dump *fadump_conf) > > static int rtas_fadump_unregister(struct fw_dump *fadump_conf) > { > - unsigned int wait_time; > int rc; > > - /* TODO: Add upper time limit for the delay */ > - do { > - rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1, > - NULL, FADUMP_UNREGISTER, &fdm, > - sizeof(struct rtas_fadump_mem_struct)); > - > - wait_time = rtas_busy_delay_time(rc); > - if (wait_time) > - mdelay(wait_time); > - } while (wait_time); > + rc = rtas_fadump_call(fadump_conf, FADUMP_UNREGISTER, &fdm, > + sizeof(struct rtas_fadump_mem_struct), "unregister"); > + if (rc == -ETIMEDOUT) > + return -ETIMEDOUT; > > if (rc) { > pr_err("Failed to un-register - unexpected error(%d).\n", rc); > @@ -259,19 +279,13 @@ static int rtas_fadump_unregister(struct fw_dump *fadump_conf) > > static int rtas_fadump_invalidate(struct fw_dump *fadump_conf) > { > - unsigned int wait_time; > int rc; > > - /* TODO: Add upper time limit for the delay */ > - do { > - rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1, > - NULL, FADUMP_INVALIDATE, fdm_active, > - sizeof(struct rtas_fadump_mem_struct)); > - > - wait_time = rtas_busy_delay_time(rc); > - if (wait_time) > - mdelay(wait_time); > - } while (wait_time); > + rc = rtas_fadump_call(fadump_conf, FADUMP_INVALIDATE, > + (void *)fdm_active, > + sizeof(struct rtas_fadump_mem_struct), "invalidate"); > + if (rc == -ETIMEDOUT) > + return -ETIMEDOUT; > > if (rc) { > pr_err("Failed to invalidate - unexpected error (%d).\n", rc); > diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.h b/arch/powerpc/platforms/pseries/rtas-fadump.h > index c109abf6befd..65fdab7b5b8d 100644 > --- a/arch/powerpc/platforms/pseries/rtas-fadump.h > +++ b/arch/powerpc/platforms/pseries/rtas-fadump.h > @@ -41,6 +41,12 @@ > #define MAX_SECTIONS 10 > #define RTAS_FADUMP_MAX_BOOT_MEM_REGS 7 > > +/* > + * Maximum time to wait for firmware to respond to an > + * ibm,configure-kernel-dump RTAS call before giving up. > + */ > +#define RTAS_FADUMP_MAX_WAIT_MS 60000U > + > /* Kernel Dump section info */ > struct rtas_fadump_section { > __be32 request_flag;