From 9ca67840c0ddf3f39407339624cef824a4f27599 Mon Sep 17 00:00:00 2001 From: Cristian Marussi Date: Thu, 6 Mar 2025 18:54:47 +0000 Subject: [PATCH 1/2] firmware: arm_scmi: Balance device refcount when destroying devices Using device_find_child() to lookup the proper SCMI device to destroy causes an unbalance in device refcount, since device_find_child() calls an implicit get_device(): this, in turns, inhibits the call of the provided release methods upon devices destruction. As a consequence, one of the structures that is not freed properly upon destruction is the internal struct device_private dev->p populated by the drivers subsystem core. KMemleak detects this situation since loading/unloding some SCMI driver causes related devices to be created/destroyed without calling any device_release method. unreferenced object 0xffff00000f583800 (size 512): comm "insmod", pid 227, jiffies 4294912190 hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff 60 36 1d 8a 00 80 ff ff ........`6...... backtrace (crc 114e2eed): kmemleak_alloc+0xbc/0xd8 __kmalloc_cache_noprof+0x2dc/0x398 device_add+0x954/0x12d0 device_register+0x28/0x40 __scmi_device_create.part.0+0x1bc/0x380 scmi_device_create+0x2d0/0x390 scmi_create_protocol_devices+0x74/0xf8 scmi_device_request_notifier+0x1f8/0x2a8 notifier_call_chain+0x110/0x3b0 blocking_notifier_call_chain+0x70/0xb0 scmi_driver_register+0x350/0x7f0 0xffff80000a3b3038 do_one_initcall+0x12c/0x730 do_init_module+0x1dc/0x640 load_module+0x4b20/0x5b70 init_module_from_file+0xec/0x158 $ ./scripts/faddr2line ./vmlinux device_add+0x954/0x12d0 device_add+0x954/0x12d0: kmalloc_noprof at include/linux/slab.h:901 (inlined by) kzalloc_noprof at include/linux/slab.h:1037 (inlined by) device_private_init at drivers/base/core.c:3510 (inlined by) device_add at drivers/base/core.c:3561 Balance device refcount by issuing a put_device() on devices found via device_find_child(). Reported-by: Alice Ryhl Closes: https://lore.kernel.org/linux-arm-kernel/Z8nK3uFkspy61yjP@arm.com/T/#mc1f73a0ea5e41014fa145147b7b839fc988ada8f CC: Sudeep Holla CC: Catalin Marinas Fixes: d4f9dddd21f3 ("firmware: arm_scmi: Add dynamic scmi devices creation") Signed-off-by: Cristian Marussi Tested-by: Alice Ryhl Message-Id: <20250306185447.2039336-1-cristian.marussi@arm.com> Signed-off-by: Sudeep Holla --- drivers/firmware/arm_scmi/bus.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c index 7af01664ce7e..3a5474015f7d 100644 --- a/drivers/firmware/arm_scmi/bus.c +++ b/drivers/firmware/arm_scmi/bus.c @@ -255,6 +255,9 @@ static struct scmi_device *scmi_child_dev_find(struct device *parent, if (!dev) return NULL; + /* Drop the refcnt bumped implicitly by device_find_child */ + put_device(dev); + return to_scmi_dev(dev); } From c23c03bf1faa1e76be1eba35bad6da6a2a7c95ee Mon Sep 17 00:00:00 2001 From: Cristian Marussi Date: Mon, 10 Mar 2025 17:58:00 +0000 Subject: [PATCH 2/2] firmware: arm_scmi: Fix timeout checks on polling path Polling mode transactions wait for a reply busy-looping without holding a spinlock, but currently the timeout checks are based only on elapsed time: as a result we could hit a false positive whenever our busy-looping thread is pre-empted and scheduled out for a time greater than the polling timeout. Change the checks at the end of the busy-loop to make sure that the polling wasn't indeed successful or an out-of-order reply caused the polling to be forcibly terminated. Fixes: 31d2f803c19c ("firmware: arm_scmi: Add sync_cmds_completed_on_ret transport flag") Reported-by: Huangjie Closes: https://lore.kernel.org/arm-scmi/20250123083323.2363749-1-jackhuang021@gmail.com/ Signed-off-by: Cristian Marussi Cc: stable@vger.kernel.org # 5.18.x Message-Id: <20250310175800.1444293-1-cristian.marussi@arm.com> Signed-off-by: Sudeep Holla --- drivers/firmware/arm_scmi/driver.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 1c75a4c9c371..0390d5ff195e 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -1248,7 +1248,8 @@ static void xfer_put(const struct scmi_protocol_handle *ph, } static bool scmi_xfer_done_no_timeout(struct scmi_chan_info *cinfo, - struct scmi_xfer *xfer, ktime_t stop) + struct scmi_xfer *xfer, ktime_t stop, + bool *ooo) { struct scmi_info *info = handle_to_scmi_info(cinfo->handle); @@ -1257,7 +1258,7 @@ static bool scmi_xfer_done_no_timeout(struct scmi_chan_info *cinfo, * in case of out-of-order receptions of delayed responses */ return info->desc->ops->poll_done(cinfo, xfer) || - try_wait_for_completion(&xfer->done) || + (*ooo = try_wait_for_completion(&xfer->done)) || ktime_after(ktime_get(), stop); } @@ -1274,15 +1275,17 @@ static int scmi_wait_for_reply(struct device *dev, const struct scmi_desc *desc, * itself to support synchronous commands replies. */ if (!desc->sync_cmds_completed_on_ret) { + bool ooo = false; + /* * Poll on xfer using transport provided .poll_done(); * assumes no completion interrupt was available. */ ktime_t stop = ktime_add_ms(ktime_get(), timeout_ms); - spin_until_cond(scmi_xfer_done_no_timeout(cinfo, - xfer, stop)); - if (ktime_after(ktime_get(), stop)) { + spin_until_cond(scmi_xfer_done_no_timeout(cinfo, xfer, + stop, &ooo)); + if (!ooo && !info->desc->ops->poll_done(cinfo, xfer)) { dev_err(dev, "timed out in resp(caller: %pS) - polling\n", (void *)_RET_IP_);