Henry's bug[1] and fix[2] prompted some further inspection by Jean.
This series provides fixes for the remaining issues Jean identified, as well as reworking the channel paths to reduce cleanup required in error paths. It is based on v6.16-rc1.
Lightly tested under qemu and on an AST2600 EVB. Further testing on platforms designed around the snoop device appreciated.
[1]: https://bugzilla.kernel.org/show_bug.cgi?id=219934 [2]: https://lore.kernel.org/all/20250401074647.21300-1-bsdhenrymartin@gmail.com/
Signed-off-by: Andrew Jeffery andrew@codeconstruct.com.au --- Changes in v2: - Address comments on v1 from Jean - Implement channel indexing using enums to avoid unnecessary tests - Switch to devm_clk_get_enabled() - Use dev_err_probe() where possible - Link to v1: https://patch.msgid.link/20250411-aspeed-lpc-snoop-fixes-v1-0-64f522e3ad6f@c...
--- Andrew Jeffery (10): soc: aspeed: lpc-snoop: Cleanup resources in stack-order soc: aspeed: lpc-snoop: Don't disable channels that aren't enabled soc: aspeed: lpc-snoop: Ensure model_data is valid soc: aspeed: lpc-snoop: Constrain parameters in channel paths soc: aspeed: lpc-snoop: Rename 'channel' to 'index' in channel paths soc: aspeed: lpc-snoop: Rearrange channel paths soc: aspeed: lpc-snoop: Switch to devm_clk_get_enabled() soc: aspeed: lpc-snoop: Use dev_err_probe() where possible soc: aspeed: lpc-snoop: Consolidate channel initialisation soc: aspeed: lpc-snoop: Lift channel config to const structs
drivers/soc/aspeed/aspeed-lpc-snoop.c | 224 +++++++++++++++++----------------- 1 file changed, 110 insertions(+), 114 deletions(-) --- base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494 change-id: 20250401-aspeed-lpc-snoop-fixes-e5d2883da3a3
Best regards,
Free the kfifo after unregistering the miscdev in aspeed_lpc_disable_snoop() as the kfifo is initialised before the miscdev in aspeed_lpc_enable_snoop().
Fixes: 3772e5da4454 ("drivers/misc: Aspeed LPC snoop output using misc chardev") Cc: stable@vger.kernel.org Cc: Jean Delvare jdelvare@suse.de Acked-by: Jean Delvare jdelvare@suse.de Signed-off-by: Andrew Jeffery andrew@codeconstruct.com.au --- drivers/soc/aspeed/aspeed-lpc-snoop.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c index ef8f355589a584d76bfac2b130ba9965c9b06ba5..59c18afa649cd672f54f947066f468f2a78c0d5d 100644 --- a/drivers/soc/aspeed/aspeed-lpc-snoop.c +++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c @@ -263,8 +263,8 @@ static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, return; }
- kfifo_free(&lpc_snoop->chan[channel].fifo); misc_deregister(&lpc_snoop->chan[channel].miscdev); + kfifo_free(&lpc_snoop->chan[channel].fifo); }
static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
Mitigate e.g. the following:
# echo 1e789080.lpc-snoop > /sys/bus/platform/drivers/aspeed-lpc-snoop/unbind ... [ 120.363594] Unable to handle kernel NULL pointer dereference at virtual address 00000004 when write [ 120.373866] [00000004] *pgd=00000000 [ 120.377910] Internal error: Oops: 805 [#1] SMP ARM [ 120.383306] CPU: 1 UID: 0 PID: 315 Comm: sh Not tainted 6.15.0-rc1-00009-g926217bc7d7d-dirty #20 NONE ... [ 120.679543] Call trace: [ 120.679559] misc_deregister from aspeed_lpc_snoop_remove+0x84/0xac [ 120.692462] aspeed_lpc_snoop_remove from platform_remove+0x28/0x38 [ 120.700996] platform_remove from device_release_driver_internal+0x188/0x200 ...
Fixes: 9f4f9ae81d0a ("drivers/misc: add Aspeed LPC snoop driver") Cc: stable@vger.kernel.org Cc: Jean Delvare jdelvare@suse.de Acked-by: Jean Delvare jdelvare@suse.de Signed-off-by: Andrew Jeffery andrew@codeconstruct.com.au --- drivers/soc/aspeed/aspeed-lpc-snoop.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c index 59c18afa649cd672f54f947066f468f2a78c0d5d..fc3a2c41cc10739f5f70ded7ac02baab6468d652 100644 --- a/drivers/soc/aspeed/aspeed-lpc-snoop.c +++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c @@ -58,6 +58,7 @@ struct aspeed_lpc_snoop_model_data { };
struct aspeed_lpc_snoop_channel { + bool enabled; struct kfifo fifo; wait_queue_head_t wq; struct miscdevice miscdev; @@ -190,6 +191,9 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, const struct aspeed_lpc_snoop_model_data *model_data = of_device_get_match_data(dev);
+ if (WARN_ON(lpc_snoop->chan[channel].enabled)) + return -EBUSY; + init_waitqueue_head(&lpc_snoop->chan[channel].wq); /* Create FIFO datastructure */ rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo, @@ -236,6 +240,8 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en);
+ lpc_snoop->chan[channel].enabled = true; + return 0;
err_misc_deregister: @@ -248,6 +254,9 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, int channel) { + if (!lpc_snoop->chan[channel].enabled) + return; + switch (channel) { case 0: regmap_update_bits(lpc_snoop->regmap, HICR5, @@ -263,6 +272,8 @@ static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, return; }
+ lpc_snoop->chan[channel].enabled = false; + /* Consider improving safety wrt concurrent reader(s) */ misc_deregister(&lpc_snoop->chan[channel].miscdev); kfifo_free(&lpc_snoop->chan[channel].fifo); }
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Andrew Jeffery