6.5-stable review patch. If anyone has any objections, please let me know.
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From: Stephen Boyd swboyd@chromium.org
[ Upstream commit 85e654c9f722853a595fa941dca60c157b707b86 ]
It's possible for interrupts to get significantly delayed to the point that callers of intel_scu_ipc_dev_command() and friends can call the function once, hit a timeout, and call it again while the interrupt still hasn't been processed. This driver will get seriously confused if the interrupt is finally processed after the second IPC has been sent with ipc_command(). It won't know which IPC has been completed. This could be quite disastrous if calling code assumes something has happened upon return from intel_scu_ipc_dev_simple_command() when it actually hasn't.
Let's avoid this scenario by simply returning -EBUSY in this case. Hopefully higher layers will know to back off or fail gracefully when this happens. It's all highly unlikely anyway, but it's better to be correct here as we have no way to know which IPC the status register is telling us about if we send a second IPC while the previous IPC is still processing.
Cc: Prashant Malani pmalani@chromium.org Cc: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Reviewed-by: Mika Westerberg mika.westerberg@linux.intel.com Fixes: ed12f295bfd5 ("ipc: Added support for IPC interrupt mode") Signed-off-by: Stephen Boyd swboyd@chromium.org Link: https://lore.kernel.org/r/20230913212723.3055315-5-swboyd@chromium.org Reviewed-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Reviewed-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/platform/x86/intel_scu_ipc.c | 40 +++++++++++++++++++--------- 1 file changed, 28 insertions(+), 12 deletions(-)
diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c index 3271f81a9c007..a68df41334035 100644 --- a/drivers/platform/x86/intel_scu_ipc.c +++ b/drivers/platform/x86/intel_scu_ipc.c @@ -265,6 +265,24 @@ static int intel_scu_ipc_check_status(struct intel_scu_ipc_dev *scu) return scu->irq > 0 ? ipc_wait_for_interrupt(scu) : busy_loop(scu); }
+static struct intel_scu_ipc_dev *intel_scu_ipc_get(struct intel_scu_ipc_dev *scu) +{ + u8 status; + + if (!scu) + scu = ipcdev; + if (!scu) + return ERR_PTR(-ENODEV); + + status = ipc_read_status(scu); + if (status & IPC_STATUS_BUSY) { + dev_dbg(&scu->dev, "device is busy\n"); + return ERR_PTR(-EBUSY); + } + + return scu; +} + /* Read/Write power control(PMIC in Langwell, MSIC in PenWell) registers */ static int pwr_reg_rdwr(struct intel_scu_ipc_dev *scu, u16 *addr, u8 *data, u32 count, u32 op, u32 id) @@ -278,11 +296,10 @@ static int pwr_reg_rdwr(struct intel_scu_ipc_dev *scu, u16 *addr, u8 *data, memset(cbuf, 0, sizeof(cbuf));
mutex_lock(&ipclock); - if (!scu) - scu = ipcdev; - if (!scu) { + scu = intel_scu_ipc_get(scu); + if (IS_ERR(scu)) { mutex_unlock(&ipclock); - return -ENODEV; + return PTR_ERR(scu); }
for (nc = 0; nc < count; nc++, offset += 2) { @@ -437,12 +454,12 @@ int intel_scu_ipc_dev_simple_command(struct intel_scu_ipc_dev *scu, int cmd, int err;
mutex_lock(&ipclock); - if (!scu) - scu = ipcdev; - if (!scu) { + scu = intel_scu_ipc_get(scu); + if (IS_ERR(scu)) { mutex_unlock(&ipclock); - return -ENODEV; + return PTR_ERR(scu); } + cmdval = sub << 12 | cmd; ipc_command(scu, cmdval); err = intel_scu_ipc_check_status(scu); @@ -482,11 +499,10 @@ int intel_scu_ipc_dev_command_with_size(struct intel_scu_ipc_dev *scu, int cmd, return -EINVAL;
mutex_lock(&ipclock); - if (!scu) - scu = ipcdev; - if (!scu) { + scu = intel_scu_ipc_get(scu); + if (IS_ERR(scu)) { mutex_unlock(&ipclock); - return -ENODEV; + return PTR_ERR(scu); }
memcpy(inbuf, in, inlen);