From 27825593c972abac86b9a4453a8c8c9a2c1ec60f Mon Sep 17 00:00:00 2001 From: Tao Zhang Date: Tue, 2 Jan 2024 07:55:12 +0530 Subject: soc: qcom: smem: remove hwspinlock from item get routine During an SSR(Sub-System Restart) process, the remoteproc driver will try to read the crash reason from SMEM. The qcom_smem_get() backing such operations does however take the hwspinlock (tcsr mutex), which might be held by the dying remoteproc. The associated timeout on the hwspin_lock_timeout_irqsave() would take care of the system not hanging forever, but the get operation will fail, unnecessarily delaying the process for the 'HWSPINLOCK_TIMEOUT' duration (currently is '1s'), and finally resulting in failure to get crash information from SMEM. This timeout can be avoided by removing the hwspinlock in the qcom_smem_get routine. SMEM ensures that the allocated item will only be visible after the new item is safe to use by following a specific order of updates. In the private partition case, qcom_smem_get_private() will use 'offset_free_uncached' as a loop boundary when looking for existing allocated items. The corresponding allocation will only update offset_free_uncached once the item is fully initialized. hdr->canary = SMEM_PRIVATE_CANARY; hdr->item = cpu_to_le16(item); hdr->size = cpu_to_le32(ALIGN(size, 8)); hdr->padding_data = cpu_to_le16(le32_to_cpu(hdr->size) - size); hdr->padding_hdr = 0; wmb(); le32_add_cpu(&phdr->offset_free_uncached, alloc_size); The global partition is similar but uses the "entry->allocated" variable to ensure the item is not visible to qcom_smem_get_global(). Signed-off-by: Tao Zhang Reviewed-by: Chris Lew Link: https://lore.kernel.org/r/20240102022512.999635-1-quic_taozhan@quicinc.com Signed-off-by: Bjorn Andersson --- drivers/soc/qcom/smem.c | 11 ----------- 1 file changed, 11 deletions(-) (limited to 'drivers/soc') diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c index 690afc9a12f4..7191fa0c087f 100644 --- a/drivers/soc/qcom/smem.c +++ b/drivers/soc/qcom/smem.c @@ -655,8 +655,6 @@ invalid_canary: void *qcom_smem_get(unsigned host, unsigned item, size_t *size) { struct smem_partition *part; - unsigned long flags; - int ret; void *ptr = ERR_PTR(-EPROBE_DEFER); if (!__smem) @@ -665,12 +663,6 @@ void *qcom_smem_get(unsigned host, unsigned item, size_t *size) if (WARN_ON(item >= __smem->item_count)) return ERR_PTR(-EINVAL); - ret = hwspin_lock_timeout_irqsave(__smem->hwlock, - HWSPINLOCK_TIMEOUT, - &flags); - if (ret) - return ERR_PTR(ret); - if (host < SMEM_HOST_COUNT && __smem->partitions[host].virt_base) { part = &__smem->partitions[host]; ptr = qcom_smem_get_private(__smem, part, item, size); @@ -681,10 +673,7 @@ void *qcom_smem_get(unsigned host, unsigned item, size_t *size) ptr = qcom_smem_get_global(__smem, item, size); } - hwspin_unlock_irqrestore(__smem->hwlock, &flags); - return ptr; - } EXPORT_SYMBOL_GPL(qcom_smem_get); -- cgit v1.2.3