From patchwork Mon Oct 14 19:29:30 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mukesh Ojha X-Patchwork-Id: 836411 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6F7871BD01F; Mon, 14 Oct 2024 19:29:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.180.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728934199; cv=none; b=MTsDIbVCeDk2i5Bn/SRR9wgEI5WYIVmmX7kueFvoaFeY/R/k4jHGgs6135/D67r0bM5p4vM4Nuv2ttCM2WHc1FIWNSvzoR74vyG8ICCH7F48//FuKD2PaaIyVqf7Gqkj/JtMgGe7E3fT2wuHzoAR7D0FMt6juqY0DOHMyckM3ho= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728934199; c=relaxed/simple; bh=IIc1taoQbO8/4lHIqvAxM5YIybXgrfDk1GH2JcKwalc=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=uUzRRimZ+Ztl9oq4Qbsvh6mVueqqSPyiAYJkvezmgLmJL92cZPb7HL+Vbf7fronGmNrq33huQpEeb1rD9w5MjQ79nhtHxuyY2TocK1DjHpLKpilFnfFOBvjYC9ysmQMPH3RXTUUNmG8NFgP1g+6QQ2YjX9OID4v3NXNZRSxKFnQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com; spf=pass smtp.mailfrom=quicinc.com; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b=aCWmSaCW; arc=none smtp.client-ip=205.220.180.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=quicinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b="aCWmSaCW" Received: from pps.filterd (m0279869.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 49EAFuio011572; Mon, 14 Oct 2024 19:29:56 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h= cc:content-transfer-encoding:content-type:date:from:message-id :mime-version:subject:to; s=qcppdkim1; bh=tephfjupl5FlMaTSdIzxef Us/LaQXuNP5qmw5NzOUts=; b=aCWmSaCW+jfT769vJPOS0rekh/sVrS2vOdnQ3n NUERPB+vyyOc41ogC9hOYzVB0Ftmg06V6bLZxbl2G2npOdUNmXTt8KLZXYmFXmtO UEGIlIG0jiCPrtKGDCDQBWWrFekPVwhTwNYitvpKQ0lV1PTOFhZr9SIGljTQ8/1i esr5uN5mpxyMS3FA+UwMoqG8I5ijKshlkCAD6mSxyzdlIBKtv3+f20DXM+2IuQPi nm34cakcNfqQOSqSvJW5/7RDI14uRrNJntGTitEDTHjrXKHwXjARydXR8D+VrxQq GntE8riH04TM4ag806y9YXXFuVF3d0tSbzOzKS8K2viDW4MQ== Received: from nasanppmta04.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 427g45dgc3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 14 Oct 2024 19:29:55 +0000 (GMT) Received: from nasanex01c.na.qualcomm.com (nasanex01c.na.qualcomm.com [10.45.79.139]) by NASANPPMTA04.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 49EJTsPg018865 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 14 Oct 2024 19:29:54 GMT Received: from hu-mojha-hyd.qualcomm.com (10.80.80.8) by nasanex01c.na.qualcomm.com (10.45.79.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Mon, 14 Oct 2024 12:29:52 -0700 From: Mukesh Ojha To: Linus Walleij CC: , , Mukesh Ojha Subject: [PATCH v3] pinmux: Use sequential access to access desc->pinmux data Date: Tue, 15 Oct 2024 00:59:30 +0530 Message-ID: <20241014192930.1539673-1-quic_mojha@quicinc.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nasanex01c.na.qualcomm.com (10.45.79.139) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: BUy4u_6cgAE9GxCewcbHKQ8caA6byKEk X-Proofpoint-ORIG-GUID: BUy4u_6cgAE9GxCewcbHKQ8caA6byKEk X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 lowpriorityscore=0 malwarescore=0 spamscore=0 impostorscore=0 bulkscore=0 mlxscore=0 priorityscore=1501 adultscore=0 clxscore=1015 suspectscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2410140138 When two client of the same gpio call pinctrl_select_state() for the same functionality, we are seeing NULL pointer issue while accessing desc->mux_owner. Let's say two processes A, B executing in pin_request() for the same pin and process A updates the desc->mux_usecount but not yet updated the desc->mux_owner while process B see the desc->mux_usecount which got updated by A path and further executes strcmp and while accessing desc->mux_owner it crashes with NULL pointer. Serialize the access to mux related setting with a mutex lock. cpu0 (process A) cpu1(process B) pinctrl_select_state() { pinctrl_select_state() { pin_request() { pin_request() { ... .... } else { desc->mux_usecount++; desc->mux_usecount && strcmp(desc->mux_owner, owner)) { if (desc->mux_usecount > 1) return 0; desc->mux_owner = owner; } } Signed-off-by: Mukesh Ojha --- Changes in v3: - Used mutex instead of spinlock as per comment from Wasim. - Covered one more function pinmux_can_be_used_for_gpio() where the lock should be taken as mux->setting is being accessed as per comment from Wasim. Changes in v2: - Used scoped_guard and renamed lock name as per suggestion from Linus.W . drivers/pinctrl/core.c | 3 + drivers/pinctrl/core.h | 1 + drivers/pinctrl/pinmux.c | 173 ++++++++++++++++++++++----------------- 3 files changed, 100 insertions(+), 77 deletions(-) diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c index 4061890a1748..b3eec63c00ba 100644 --- a/drivers/pinctrl/core.c +++ b/drivers/pinctrl/core.c @@ -220,6 +220,9 @@ static int pinctrl_register_one_pin(struct pinctrl_dev *pctldev, /* Set owner */ pindesc->pctldev = pctldev; +#ifdef CONFIG_PINMUX + mutex_init(&pindesc->mux_lock); +#endif /* Copy basic pin info */ if (pin->name) { diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h index 4e07707d2435..d6c24978e708 100644 --- a/drivers/pinctrl/core.h +++ b/drivers/pinctrl/core.h @@ -177,6 +177,7 @@ struct pin_desc { const char *mux_owner; const struct pinctrl_setting_mux *mux_setting; const char *gpio_owner; + struct mutex mux_lock; #endif }; diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c index 02033ea1c643..0743190da59e 100644 --- a/drivers/pinctrl/pinmux.c +++ b/drivers/pinctrl/pinmux.c @@ -14,6 +14,7 @@ #include #include +#include #include #include #include @@ -93,6 +94,7 @@ bool pinmux_can_be_used_for_gpio(struct pinctrl_dev *pctldev, unsigned int pin) if (!desc || !ops) return true; + guard(mutex)(&desc->mux_lock); if (ops->strict && desc->mux_usecount) return false; @@ -127,29 +129,31 @@ static int pin_request(struct pinctrl_dev *pctldev, dev_dbg(pctldev->dev, "request pin %d (%s) for %s\n", pin, desc->name, owner); - if ((!gpio_range || ops->strict) && - desc->mux_usecount && strcmp(desc->mux_owner, owner)) { - dev_err(pctldev->dev, - "pin %s already requested by %s; cannot claim for %s\n", - desc->name, desc->mux_owner, owner); - goto out; - } + scoped_guard(mutex, &desc->mux_lock) { + if ((!gpio_range || ops->strict) && + desc->mux_usecount && strcmp(desc->mux_owner, owner)) { + dev_err(pctldev->dev, + "pin %s already requested by %s; cannot claim for %s\n", + desc->name, desc->mux_owner, owner); + goto out; + } - if ((gpio_range || ops->strict) && desc->gpio_owner) { - dev_err(pctldev->dev, - "pin %s already requested by %s; cannot claim for %s\n", - desc->name, desc->gpio_owner, owner); - goto out; - } + if ((gpio_range || ops->strict) && desc->gpio_owner) { + dev_err(pctldev->dev, + "pin %s already requested by %s; cannot claim for %s\n", + desc->name, desc->gpio_owner, owner); + goto out; + } - if (gpio_range) { - desc->gpio_owner = owner; - } else { - desc->mux_usecount++; - if (desc->mux_usecount > 1) - return 0; + if (gpio_range) { + desc->gpio_owner = owner; + } else { + desc->mux_usecount++; + if (desc->mux_usecount > 1) + return 0; - desc->mux_owner = owner; + desc->mux_owner = owner; + } } /* Let each pin increase references to this module */ @@ -178,12 +182,14 @@ static int pin_request(struct pinctrl_dev *pctldev, out_free_pin: if (status) { - if (gpio_range) { - desc->gpio_owner = NULL; - } else { - desc->mux_usecount--; - if (!desc->mux_usecount) - desc->mux_owner = NULL; + scoped_guard(mutex, &desc->mux_lock) { + if (gpio_range) { + desc->gpio_owner = NULL; + } else { + desc->mux_usecount--; + if (!desc->mux_usecount) + desc->mux_owner = NULL; + } } } out: @@ -219,15 +225,17 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, return NULL; } - if (!gpio_range) { - /* - * A pin should not be freed more times than allocated. - */ - if (WARN_ON(!desc->mux_usecount)) - return NULL; - desc->mux_usecount--; - if (desc->mux_usecount) - return NULL; + scoped_guard(mutex, &desc->mux_lock) { + if (!gpio_range) { + /* + * A pin should not be freed more times than allocated. + */ + if (WARN_ON(!desc->mux_usecount)) + return NULL; + desc->mux_usecount--; + if (desc->mux_usecount) + return NULL; + } } /* @@ -239,13 +247,15 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, else if (ops->free) ops->free(pctldev, pin); - if (gpio_range) { - owner = desc->gpio_owner; - desc->gpio_owner = NULL; - } else { - owner = desc->mux_owner; - desc->mux_owner = NULL; - desc->mux_setting = NULL; + scoped_guard(mutex, &desc->mux_lock) { + if (gpio_range) { + owner = desc->gpio_owner; + desc->gpio_owner = NULL; + } else { + owner = desc->mux_owner; + desc->mux_owner = NULL; + desc->mux_setting = NULL; + } } module_put(pctldev->owner); @@ -458,7 +468,8 @@ int pinmux_enable_setting(const struct pinctrl_setting *setting) pins[i]); continue; } - desc->mux_setting = &(setting->data.mux); + scoped_guard(mutex, &desc->mux_lock) + desc->mux_setting = &(setting->data.mux); } ret = ops->set_mux(pctldev, setting->data.mux.func, @@ -472,8 +483,10 @@ int pinmux_enable_setting(const struct pinctrl_setting *setting) err_set_mux: for (i = 0; i < num_pins; i++) { desc = pin_desc_get(pctldev, pins[i]); - if (desc) - desc->mux_setting = NULL; + if (desc) { + scoped_guard(mutex, &desc->mux_lock) + desc->mux_setting = NULL; + } } err_pin_request: /* On error release all taken pins */ @@ -492,6 +505,7 @@ void pinmux_disable_setting(const struct pinctrl_setting *setting) unsigned int num_pins = 0; int i; struct pin_desc *desc; + bool is_equal; if (pctlops->get_group_pins) ret = pctlops->get_group_pins(pctldev, setting->data.mux.group, @@ -517,7 +531,10 @@ void pinmux_disable_setting(const struct pinctrl_setting *setting) pins[i]); continue; } - if (desc->mux_setting == &(setting->data.mux)) { + scoped_guard(mutex, &desc->mux_lock) + is_equal = (desc->mux_setting == &(setting->data.mux)); + + if (is_equal) { pin_free(pctldev, pins[i], NULL); } else { const char *gname; @@ -608,40 +625,42 @@ static int pinmux_pins_show(struct seq_file *s, void *what) if (desc == NULL) continue; - if (desc->mux_owner && - !strcmp(desc->mux_owner, pinctrl_dev_get_name(pctldev))) - is_hog = true; - - if (pmxops->strict) { - if (desc->mux_owner) - seq_printf(s, "pin %d (%s): device %s%s", - pin, desc->name, desc->mux_owner, + scoped_guard(mutex, &desc->mux_lock) { + if (desc->mux_owner && + !strcmp(desc->mux_owner, pinctrl_dev_get_name(pctldev))) + is_hog = true; + + if (pmxops->strict) { + if (desc->mux_owner) + seq_printf(s, "pin %d (%s): device %s%s", + pin, desc->name, desc->mux_owner, + is_hog ? " (HOG)" : ""); + else if (desc->gpio_owner) + seq_printf(s, "pin %d (%s): GPIO %s", + pin, desc->name, desc->gpio_owner); + else + seq_printf(s, "pin %d (%s): UNCLAIMED", + pin, desc->name); + } else { + /* For non-strict controllers */ + seq_printf(s, "pin %d (%s): %s %s%s", pin, desc->name, + desc->mux_owner ? desc->mux_owner + : "(MUX UNCLAIMED)", + desc->gpio_owner ? desc->gpio_owner + : "(GPIO UNCLAIMED)", is_hog ? " (HOG)" : ""); - else if (desc->gpio_owner) - seq_printf(s, "pin %d (%s): GPIO %s", - pin, desc->name, desc->gpio_owner); + } + + /* If mux: print function+group claiming the pin */ + if (desc->mux_setting) + seq_printf(s, " function %s group %s\n", + pmxops->get_function_name(pctldev, + desc->mux_setting->func), + pctlops->get_group_name(pctldev, + desc->mux_setting->group)); else - seq_printf(s, "pin %d (%s): UNCLAIMED", - pin, desc->name); - } else { - /* For non-strict controllers */ - seq_printf(s, "pin %d (%s): %s %s%s", pin, desc->name, - desc->mux_owner ? desc->mux_owner - : "(MUX UNCLAIMED)", - desc->gpio_owner ? desc->gpio_owner - : "(GPIO UNCLAIMED)", - is_hog ? " (HOG)" : ""); + seq_putc(s, '\n'); } - - /* If mux: print function+group claiming the pin */ - if (desc->mux_setting) - seq_printf(s, " function %s group %s\n", - pmxops->get_function_name(pctldev, - desc->mux_setting->func), - pctlops->get_group_name(pctldev, - desc->mux_setting->group)); - else - seq_putc(s, '\n'); } mutex_unlock(&pctldev->mutex);