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Wed, 6 May 2026 19:21:57 +0000 (GMT) Message-ID: <7bef2ce2-1fd3-4648-8c78-d3c5e07a1f9f@linux.ibm.com> Date: Thu, 7 May 2026 00:51:55 +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 v2] 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: <20260406061542.22354-1-litaliano00.contact@gmail.com> <20260419065039.23495-1-adri.vero.dev@gmail.com> Content-Language: en-US From: Sourabh Jain In-Reply-To: <20260419065039.23495-1-adri.vero.dev@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA2MDE4NyBTYWx0ZWRfX5KbN/bh6cT3T Yqk7zD21WyoYLGCR8h3OIJdGyXztvt+XYUEWwwh5Yr8iXQ3njCOYaNPTE3bJ+khL64EJe8OEGY2 zzsG0os+ID+C58WM/XHrUx5/CyxJtoKOX7kcYB6FIW6sbLjldvkHpZwAEGC0cl4+rtlC45ZdBEW 9EK5Rs7lYBH4QmRAeWUZz3a2t85Gk6hPNtrDqKdyLlyjQQ5bvpX0HpyFF6WMRd6U9rrjc6Tg9ZS K9XW90QwuA1S/+a2O2YEPTwPQz/ueRldK39T2lSgY070mpGFpiobbgU1usvchgTB7wRqbSzSmDG K5D4xWq2ugpf5fkWErof8aovALRG1JRzf6ivgyFokK1WydtBUrmasqlCtpacljb/vQw6kRZsZL6 Cs6/1p+ADYIhmSATn0Tuz58EIDsZnx0q+wClWmkhFaqv3mEu3gyqwVSnCwopSB5v9d7PgoR+epq dPUiH1rahPFi8heP81Q== X-Authority-Analysis: v=2.4 cv=J4GaKgnS c=1 sm=1 tr=0 ts=69fb94db cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=2weaD-oI5XvQ2TJmH0sA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: ia2UIzHSQ0ExLMhG53H9KQ7AEopCBSRm X-Proofpoint-ORIG-GUID: 7Iat4JjmCeDpU60oFpuROP7TUkLOGCt8 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_01,2026-05-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 malwarescore=0 bulkscore=0 suspectscore=0 priorityscore=1501 spamscore=0 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605060187 On 19/04/26 12:20, 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 > --- > 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 eceb32893..3bb4ac2ab 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 c109abf6b..65fdab7b5 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; Changes look good to me. Feel free to add: Reviewed-by: Sourabh Jain While testing this patch I realized that fadump prints below message when registered is successfully fadump: Registration is successful But there is no message when fadump is unregistered successfully. I think it is good to log that event.  I will send a separate patch for this. - Sourabh Jain