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Sun, 30 Aug 2026 13:52:54 -0700 (PDT) From: Dmitry Torokhov Date: Sun, 30 Aug 2026 13:52:47 -0700 Subject: [PATCH 2/7] Input: gscps2 - use RCU for ps2port_list and manage it in open/close Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260830-gscps2-v1-2-c733d4cae7f9@gmail.com> References: <20260830-gscps2-v1-0-c733d4cae7f9@gmail.com> In-Reply-To: <20260830-gscps2-v1-0-c733d4cae7f9@gmail.com> To: "James E.J. Bottomley" , Helge Deller Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, linux-parisc@vger.kernel.org, sashiko-bot@kernel.org X-Mailer: b4 0.16-dev-b242f Managing ps2port_list in gscps2_probe() and gscps2_remove() had two issues: - in gscps2_remove(), serio_unregister_port() frees the serio port, but because the port remained in ps2port_list until later in remove, a shared interrupt firing on another CPU could traverse ps2port_list and dereference the freed serio port - ps2port_list additions and deletions in probe/remove raced locklessly against list traversals in gscps2_interrupt(). Convert ps2port_list traversal in gscps2_interrupt() to use RCU, and move list management to gscps2_open() and gscps2_close(). When serio_unregister_port() runs during device removal, serio_close() is invoked, cleanly taking the port out of ps2port_list before the serio structure is destroyed, while maintaining active hardware communication during child driver disconnect. Reported-by: sashiko-bot@kernel.org Assisted-by: LLM Signed-off-by: Dmitry Torokhov --- drivers/input/serio/gscps2.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/drivers/input/serio/gscps2.c b/drivers/input/serio/gscps2.c index b82c56ba8ff7..5b6e311f8a02 100644 --- a/drivers/input/serio/gscps2.c +++ b/drivers/input/serio/gscps2.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -195,6 +196,7 @@ struct gscps2port { int id; }; +static DEFINE_SPINLOCK(ps2port_list_lock); static LIST_HEAD(ps2port_list); /* @@ -292,14 +294,16 @@ static irqreturn_t gscps2_interrupt(int irq, void *dev) { struct gscps2port *ps2port; - list_for_each_entry(ps2port, &ps2port_list, node) { + guard(rcu)(); + + list_for_each_entry_rcu(ps2port, &ps2port_list, node) { guard(spinlock_irqsave)(&ps2port->lock); gscps2_read_data(ps2port); - } /* list_for_each_entry */ + } /* all data was read from the ports - now report the data to upper layer */ - list_for_each_entry(ps2port, &ps2port_list, node) { + list_for_each_entry_rcu(ps2port, &ps2port_list, node) { if (gscps2_report_data(ps2port)) { /* More data ready - break early to restart interrupt */ break; @@ -397,6 +401,9 @@ static int gscps2_open(struct serio *port) gscps2_reset(ps2port); + scoped_guard(spinlock_irqsave, &ps2port_list_lock) + list_add_tail_rcu(&ps2port->node, &ps2port_list); + /* enable it */ gscps2_enable(ps2port, true); @@ -413,6 +420,11 @@ static void gscps2_close(struct serio *port) struct gscps2port *ps2port = port->port_data; gscps2_enable(ps2port, false); + + scoped_guard(spinlock_irqsave, &ps2port_list_lock) + list_del_rcu(&ps2port->node); + + synchronize_rcu(); } /** @@ -446,6 +458,7 @@ static int __init gscps2_probe(struct parisc_device *dev) ps2port->port = serio; ps2port->padev = dev; + INIT_LIST_HEAD(&ps2port->node); ps2port->addr = ioremap(hpa, GSC_STATUS + 4); if (!ps2port->addr) { ret = -ENOMEM; @@ -501,8 +514,6 @@ static int __init gscps2_probe(struct parisc_device *dev) serio_register_port(ps2port->port); - list_add_tail(&ps2port->node, &ps2port_list); - return 0; fail: @@ -539,12 +550,10 @@ static void __exit gscps2_remove(struct parisc_device *dev) serio_unregister_port(ps2port->port); free_irq(dev->irq, ps2port); gscps2_flush(ps2port); - list_del(&ps2port->node); iounmap(ps2port->addr); #if 0 release_mem_region(dev->hpa, GSC_STATUS + 4); #endif - dev_set_drvdata(&dev->dev, NULL); kfree(ps2port); } -- 2.55.0.897.gb25b4bd76c-goog