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Sat, 13 Mar 2021 23:56:51 -0800 (PST) Date: Sun, 14 Mar 2021 16:56:44 +0900 From: William Breathitt Gray To: Fabrice Gasnier Cc: jic23@kernel.org, kamel.bouhara@bootlin.com, gwendal@chromium.org, david@lechnology.com, linux-iio@vger.kernel.org, patrick.havelange@essensium.com, alexandre.belloni@bootlin.com, mcoquelin.stm32@gmail.com, linux-kernel@vger.kernel.org, o.rempel@pengutronix.de, Dan Carpenter , kernel@pengutronix.de, fabrice.gasnier@st.com, syednwaris@gmail.com, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, alexandre.torgue@st.com Subject: Re: [Linux-stm32] [PATCH v9 22/33] counter: Internalize sysfs interface code Message-ID: References: <377a1552e7794ca4d998d840c06ba4a109214863.1615293276.git.vilhelm.gray@gmail.com> MIME-Version: 1.0 In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210314_075655_407148_CEFACB98 X-CRM114-Status: GOOD ( 27.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============7680054831315247515==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============7680054831315247515== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="OX+k5tirlBCrf7ng" Content-Disposition: inline --OX+k5tirlBCrf7ng Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 =3D 0; > > + size_t index; > > + > > + for (index =3D 0; index < num_enums; index++) > > + len +=3D sysfs_emit(buf + len, "%s\n", strs[enums[index]]); > > + > > + return len; > > +} > > + > > +static ssize_t strs_available_show(const struct counter_available *con= st avail, > > + char *buf) > > +{ > > + size_t len =3D 0; > > + size_t index; > > + > > + for (index =3D 0; index < avail->num_items; index++) > > + len +=3D sysfs_emit(buf + len, "%s\n", avail->strs[index]); > > + > > + return len; > > +} >=20 > Hi William, >=20 > I was willing to do some testing on this series, on the stm32 counter > drivers, since we released few fixes around them. >=20 > 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 regist= er > - counter: stm32-timer-cnt: fix ceiling write max value > counter: stm32-timer-cnt: Report count function when SLAVE_MODE_DISABLED >=20 >=20 > 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. >=20 > For both the "stm32-lptimer-cnt", there are 2 functions currently I get > 1 stack dump. Only the "increase" function is printed correctly. >=20 > For the "stm32-timer-cnt", there are 4 functions currently, I get 3 > stack dumps. Only the "increase" function is printed correctly >=20 > Sample log for "stm32-timer-cnt: >=20 > root@stm32mp1:/sys/devices/platform/soc/44000000.timer/44000000.timer:cou= nter/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] [] (unwind_backtrace) from [] > (show_stack+0x10/0x14) > [ 4689.281942] [] (show_stack) from [] > (dump_stack+0xc0/0xd4) > [ 4689.289199] [] (dump_stack) from [] > (__warn+0xec/0x148) > [ 4689.296194] [] (__warn) from [] > (warn_slowpath_fmt+0x98/0xbc) > [ 4689.303714] [] (warn_slowpath_fmt) from [] > (sysfs_emit+0x88/0x94) > [ 4689.311586] [] (sysfs_emit) from [] > (counter_comp_available_show+0x11c/0x1a4 [counter]) > [ 4689.321382] [] (counter_comp_available_show [counter]) from > [] (dev_attr_show+0x18/0x48) > [ 4689.331263] [] (dev_attr_show) from [] > (sysfs_kf_seq_show+0x88/0xf0) > [ 4689.339394] [] (sysfs_kf_seq_show) from [] > (seq_read_iter+0x1a4/0x554) > [ 4689.347703] [] (seq_read_iter) from [] > (vfs_read+0x1ac/0x2c4) > [ 4689.355224] [] (vfs_read) from [] > (ksys_read+0x64/0xdc) > [ 4689.362219] [] (ksys_read) from [] > (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 >=20 > I get similar backtrace with other _available attributes: > $ cat signal0_action_available > $ cat signal1_action_available >=20 > Do you think I'm doing something wrong ? >=20 > I tested then "quadrature x4" on the timer driver... It seems all fine. >=20 > Best regards > Fabrice >=20 > > + > > +static ssize_t counter_comp_available_show(struct device *dev, > > + struct device_attribute *attr, > > + char *buf) > > +{ > > + const struct counter_attribute *const a =3D to_counter_attribute(attr= ); > > + const struct counter_count *const count =3D a->parent; > > + const struct counter_synapse *const synapse =3D a->comp.priv; > > + const struct counter_available *const avail =3D 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 --OX+k5tirlBCrf7ng Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEk5I4PDJ2w1cDf/bghvpINdm7VJIFAmBNwZwACgkQhvpINdm7 VJJ55Q//SClbiv5JgGdODpISijHCc9CIVrAHGlf42xDTNs2jX1lpJsUDg6YBC+VJ LEXB3kq5q4IuqwZm83PNlUm0KeSmzd6FlvBiahUVxF/6r+sb18d4UoN3RpCdEeYe /9Ck1Okjk7MBQEg289zNc78gT+juobAS0G9gzHBn9xTKWvhUQLe89G8or2u/mey1 Udz8InSR3WhNFEKosZbEqnJU1mTJHP39XQX3nXfVPi/LsOQGBWPGtvcylITg/eMd fDLa+j0ShR6fZ3VTBSCLKfqnzmkNSI9qNDhSRQhsS6c9jWVj7z4JWUvQknOVoeGC 55ygLX9OlwrDauS0ULxTLxcv4Jjg2kWvnoBS45+UXlwmr/0WkDls3wpEnZaduQdf +BeL5LQxBat4W24XQVbd+B9mRWg4Yt6MerrlzWe2iUt+cCzUsXhU4DZ3pLCH8bBU +MGcxa4vfcR63ip8JfPwhoPp88uf1Wihv3YMkLgnfvkhszw/an3t6KTPmfZQBlva uOD9+G6U9W+MXVjQTYWL2/lmdh7C0TdArjoqx0UcPvqrxvQYIlvCnAH3RRk1zzUP MGstKkUhQKZfeRuOQ6kniN2t1J+6ExHEpyfwpDyvmdYAk80y+9xoHgSUiUVJw+kK 2+ppGOyFCqUz4e+V6DNVTe9UGBdUPv5tlWetaWrVsChflOZf1q8= =SRv8 -----END PGP SIGNATURE----- --OX+k5tirlBCrf7ng-- --===============7680054831315247515== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============7680054831315247515==--