On 3/14/21 10:08 AM, William Breathitt Gray wrote: > On Sun, Mar 14, 2021 at 04:56:44PM +0900, William Breathitt Gray wrote: >> On Fri, Mar 12, 2021 at 04:02:42PM +0100, Fabrice Gasnier wrote: >>> On 3/9/21 2:19 PM, William Breathitt Gray wrote: >>>> +static ssize_t enums_available_show(const u32 *const enums, >>>> + const size_t num_enums, >>>> + const char *const strs[], char *buf) >>>> +{ >>>> + size_t len = 0; >>>> + size_t index; >>>> + >>>> + for (index = 0; index < num_enums; index++) >>>> + len += sysfs_emit(buf + len, "%s\n", strs[enums[index]]); >>>> + >>>> + return len; >>>> +} >>>> + >>>> +static ssize_t strs_available_show(const struct counter_available *const avail, >>>> + char *buf) >>>> +{ >>>> + size_t len = 0; >>>> + size_t index; >>>> + >>>> + for (index = 0; index < avail->num_items; index++) >>>> + len += sysfs_emit(buf + len, "%s\n", avail->strs[index]); >>>> + >>>> + return len; >>>> +} >>> >>> Hi William, >>> >>> I was willing to do some testing on this series, on the stm32 counter >>> drivers, since we released few fixes around them. >>> >>> I tried to apply this series against current testing branch, with few >>> patches applied (so it applies cleanly): >>> - dt-bindings: counter: add interrupt-counter binding >>> - counter: add IRQ or GPIO based counter >>> - counter: stm32-timer-cnt: fix ceiling miss-alignment with reload register >>> - counter: stm32-timer-cnt: fix ceiling write max value >>> counter: stm32-timer-cnt: Report count function when SLAVE_MODE_DISABLED >>> >>> >>> For both the "stm32-lptimer-cnt" and "stm32-timer-cnt" drivers, I get a >>> warning message and stack dump in "sysfs_emit" when reading the >>> available functions from sysfs. >>> I started to do some testing on v8 of this series last week. I didn't >>> noticed that. >>> >>> For both the "stm32-lptimer-cnt", there are 2 functions currently I get >>> 1 stack dump. Only the "increase" function is printed correctly. >>> >>> For the "stm32-timer-cnt", there are 4 functions currently, I get 3 >>> stack dumps. Only the "increase" function is printed correctly >>> >>> Sample log for "stm32-timer-cnt: >>> >>> root@stm32mp1:/sys/devices/platform/soc/44000000.timer/44000000.timer:counter/counter0# >>> cat count0/function_available >>> [ 4689.195506] ------------[ cut here ]------------ >>> [ 4689.198747] WARNING: CPU: 1 PID: 5841 at fs/sysfs/file.c:737 >>> sysfs_emit+0x88/0x94 >>> [ 4689.206233] invalid sysfs_emit: buf:f4a66208 >>> [ 4689.210553] Modules linked in: sha256_generic libsha256 sha256_arm >>> cfg80211 panel_orisetech_otm8009a snd_soc_hdmi_codec >>> snd_soc_stm32_sai_sub stm32_lptimers >>> [ 4689.261444] CPU: 1 PID: 5841 Comm: cat Tainted: G W >>> 5.12.0-rc1 #534 >>> [ 4689.268999] Hardware name: STM32 (Device Tree Support) >>> [ 4689.274166] [<c0310b38>] (unwind_backtrace) from [<c030b4ec>] >>> (show_stack+0x10/0x14) >>> [ 4689.281942] [<c030b4ec>] (show_stack) from [<c0fede70>] >>> (dump_stack+0xc0/0xd4) >>> [ 4689.289199] [<c0fede70>] (dump_stack) from [<c0345624>] >>> (__warn+0xec/0x148) >>> [ 4689.296194] [<c0345624>] (__warn) from [<c0fe9e90>] >>> (warn_slowpath_fmt+0x98/0xbc) >>> [ 4689.303714] [<c0fe9e90>] (warn_slowpath_fmt) from [<c0548ee0>] >>> (sysfs_emit+0x88/0x94) >>> [ 4689.311586] [<c0548ee0>] (sysfs_emit) from [<bf115de8>] >>> (counter_comp_available_show+0x11c/0x1a4 [counter]) >>> [ 4689.321382] [<bf115de8>] (counter_comp_available_show [counter]) from >>> [<c0a21b70>] (dev_attr_show+0x18/0x48) >>> [ 4689.331263] [<c0a21b70>] (dev_attr_show) from [<c0549014>] >>> (sysfs_kf_seq_show+0x88/0xf0) >>> [ 4689.339394] [<c0549014>] (sysfs_kf_seq_show) from [<c04da6e8>] >>> (seq_read_iter+0x1a4/0x554) >>> [ 4689.347703] [<c04da6e8>] (seq_read_iter) from [<c04af6f0>] >>> (vfs_read+0x1ac/0x2c4) >>> [ 4689.355224] [<c04af6f0>] (vfs_read) from [<c04afc20>] >>> (ksys_read+0x64/0xdc) >>> [ 4689.362219] [<c04afc20>] (ksys_read) from [<c03000c0>] >>> (ret_fast_syscall+0x0/0x58) >>> [ 4689.369827] Exception stack(0xc7261fa8 to 0xc7261ff0) >>> [ 4689.374906] 1fa0: 00000000 00020000 00000003 >>> b6f35000 00020000 00000000 >>> [ 4689.383126] 1fc0: 00000000 00020000 b6f56ce0 00000003 00000003 >>> 00000000 00020000 00000000 >>> [ 4689.391344] 1fe0: 00000003 be8239a8 410bff27 4104c066 >>> ... >>> 2 more stack dumps follow >>> ... >>> [ 4689.810479] ---[ end trace 59ed79949efe984c ]--- >>> increase >>> >>> I get similar backtrace with other _available attributes: >>> $ cat signal0_action_available >>> $ cat signal1_action_available >>> >>> Do you think I'm doing something wrong ? >>> >>> I tested then "quadrature x4" on the timer driver... It seems all fine. >>> >>> Best regards >>> Fabrice >>> >>>> + >>>> +static ssize_t counter_comp_available_show(struct device *dev, >>>> + struct device_attribute *attr, >>>> + char *buf) >>>> +{ >>>> + const struct counter_attribute *const a = to_counter_attribute(attr); >>>> + const struct counter_count *const count = a->parent; >>>> + const struct counter_synapse *const synapse = a->comp.priv; >>>> + const struct counter_available *const avail = a->comp.priv; >>>> + >>>> + switch (a->comp.type) { >>>> + case COUNTER_COMP_FUNCTION: >>>> + return enums_available_show(count->functions_list, >>>> + count->num_functions, >>>> + counter_function_str, buf); >>>> + case COUNTER_COMP_SYNAPSE_ACTION: >>>> + return enums_available_show(synapse->actions_list, >>>> + synapse->num_actions, >>>> + counter_synapse_action_str, buf); >>>> + case COUNTER_COMP_ENUM: >>>> + return strs_available_show(avail, buf); >>>> + case COUNTER_COMP_COUNT_MODE: >>>> + return enums_available_show(avail->enums, avail->num_items, >>>> + counter_count_mode_str, buf); >>>> + default: >>>> + return -EINVAL; >>>> + } >>>> +} >> >> Hi Fabrice, >> >> I can confirm that I'm hitting this regression as well with the >> 104-quad-8 driver. The warning seems to be caused by the >> offset_in_page(buf) check in sysfs_emit(). It looks like the first loop >> in enums_available_show() calls sysfs_emit() correctly, but subsequent >> loops have an invalid buf offset. >> >> The enums_available_show() callback is rather simple: call sysfs_emit() >> for each enum string and increment buf by the length written each time. >> I haven't modified this function since v8, so I am somewhat confused >> about why the buf offset would be invalid here now. I wonder if there >> has been a change somewhere else in the kernel that is causing >> sysfs_emit() to now return an incorrect length. >> >> William Breathitt Gray > > Fabrice, > > Would you be able to check the values of buf and len before they enter > sysfs_emit()? I think redefining the enums_available_show() function > like this should suffice: > > static ssize_t enums_available_show(const u32 *const enums, > const size_t num_enums, > const char *const strs[], char *buf) > { > size_t len = 0; > size_t index; > > for (index = 0; index < num_enums; index++){ > pr_info("buf: %p\tbuf+len: %p\tlen: %zu\n", buf, buf + len, len); > len += sysfs_emit(buf + len, "%s\n", strs[enums[index]]); > } > > return len; > } > > I want to see whether the issue is due to the sysfs_emit() return value > or the value of buf. Hi William, Sorry for the delay, I'm getting strange results on buf+len. Here's the result I'm getting with same test as above: [ 170.190995] buf: 5daf3333 buf+len: 5daf3333 len: 0 [ 170.194383] buf: 5daf3333 buf+len: 22c37039 len: 9 [ 170.199268] ------------[ cut here ]------------ ... [ 170.404810] buf: 5daf3333 buf+len: 22c37039 len: 9 [ 170.409663] ------------[ cut here ]------------ ... [ 170.615265] buf: 5daf3333 buf+len: 22c37039 len: 9 [ 170.620117] ------------[ cut here ]------------ ... increase Hope this helps, Fabrice > > Thank you, > > William Breathitt Gray >