From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-201.mailbox.org (mout-p-201.mailbox.org [80.241.56.171]) (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 32FF92DC764; Sat, 11 Jul 2026 15:21:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783783298; cv=none; b=FOVGyqLbdjPHf851VxQLoDHq81OuyHvGMvAhdOlVvBjxR5A3poYc6yuEIM97AOIr7aClmhcijNlRUkGqC0O+ESCh3R46RlRlKkG9PaLTnZrZb6WGf+iwOJG2NryJpR46h+nLyTRMjG+s1k0pviFGERzAIxSeOUSRLfDZJ0NbnQM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783783298; c=relaxed/simple; bh=UvTBMgm38RY8zEXs2NATRQuun95jyORW9mMSNxmV5FA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Fb+I7RJFnyLLdS0kz+RMY1Y3xl1mRQEJgAfcDLn6kCJcv5hy1R4rzNgS/Drl80BZ2iDmJVb8Z8ShF7LY7ZwAT4dNF9n0Lhj0BNqbeIgL1KIDWaxQmtEm33h9CWfDDlD91kBCeoVW6DZovvUH1iZHTQ6Cm/vzsBWLR2Y0fm6BU/U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=vNC6Nr8Q; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=adq2ry/u; arc=none smtp.client-ip=80.241.56.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="vNC6Nr8Q"; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="adq2ry/u" Received: from smtp102.mailbox.org (smtp102.mailbox.org [10.196.197.102]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA512) (No client certificate requested) by mout-p-201.mailbox.org (Postfix) with ESMTPS id 4gyC8s58czzMlFw; Sat, 11 Jul 2026 17:21:33 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1783783293; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+/l7Xlwgc32SRo4MSsc6Qw/JiVZgPEEXCYL8AXhdB7g=; b=vNC6Nr8Qu+GAEZlEV//+bczXk5JjcPJWznDQiXnBFy48QVgQnoKKU6G0BwyiTsYd/cPzSl N2fsc9kmUUDjl/F7JMWNChYNPd4h5ors5BL8n/kDs55QGNLeWi60GgMVxZ/6+DxBfn1KHH Nx+FJq10I7wAfD/bMZtaoOh3BRX4DQLdw04vhMvksj+2ZAsK08ACiXzlu0H0FXVrPufl9o MeAuDi6b2W2KdZsjNaeYhaIsJ/jq+thJaE5aUXQXpl1JhtAI1MeKVnSYZH390u27CdSlot J+on4CbeW+nJOgukoXg8+k8/kAJu1gluMBR7muSIAkpAmsPpyiuEpaeqTs0cgw== From: Maurice Hieronymus DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1783783291; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+/l7Xlwgc32SRo4MSsc6Qw/JiVZgPEEXCYL8AXhdB7g=; b=adq2ry/uVyggAKv2tF+LozCCQKi72ZDJ5hkkep0oXTPNmMLzUhP2jR2qG1EoapxFVvxXAo Pn4WlzKfzjyGrEzeCbit25hbfaoOumavShFYHsb7YpfugGHtxo6IaohAuw5EuEPvoI/fWk +El95ldUl99KQu8xxoOMq2VGA/oNSgfncQ5f8/1LGzdO+oGTr9Eh/jgBukgFifgxOmK63v nzXEOCH2MmsrNekjdoef+T9BwPg1lQe4fyVzSCHLwIjQaKvhTYNvEYMZhK01GxfKVKiy3E 9R1HoWfC+Mj3jMe7irk53eANjShhgTjnn/VRyReCnFnEQdYUhYEKkBDp9oLZUg== Date: Sat, 11 Jul 2026 17:21:06 +0200 Subject: [PATCH 1/2] PCI: Replace pci_dev->is_busmaster with accessors Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260711-pci-dev-flags-v1-1-2fcf2811138c@mailbox.org> References: <20260711-pci-dev-flags-v1-0-2fcf2811138c@mailbox.org> In-Reply-To: <20260711-pci-dev-flags-v1-0-2fcf2811138c@mailbox.org> To: Edward Cree , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Bjorn Helgaas , Justin Tee , Paul Ely , "James E.J. Bottomley" , "Martin K. Petersen" , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Miguel Ojeda , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?utf-8?q?Onur_=C3=96zkan?= , Borislav Petkov , Tony Luck Cc: Danilo Krummrich , rust-for-linux@vger.kernel.org, netdev@vger.kernel.org, linux-net-drivers@amd.com, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, xen-devel@lists.xenproject.org, linux-edac@vger.kernel.org, Maurice Hieronymus X-Developer-Signature: v=1; a=ed25519-sha256; t=1783783272; l=8697; i=mhi@mailbox.org; s=20260525; h=from:subject:message-id; bh=UvTBMgm38RY8zEXs2NATRQuun95jyORW9mMSNxmV5FA=; b=pQSZj8wz+D4fY0P5+pOyu6Es4y8tnTZt88mjrg56g8MYWNwlgOVIFy3c+5QCEWgww49IBV8hS 52acPwOKzvHB3t4voqsaavWiw/3UmrRwsmlYpGKuMcaEd6RHjAKdJJ5 X-Developer-Key: i=mhi@mailbox.org; a=ed25519; pk=AHlEkGG3hpXZHntlEzF42Ip/LFyXWOgsNUvaHqAnV80= X-MBO-RS-META: er15gbymiuy8xweyxi8sy8tna1xynnrb X-MBO-RS-ID: 4dfa2ffa0a7b52f860d `is_busmaster` is one bit of a ~60-bit C bitfield in `struct pci_dev`. Bits sharing a bitfield word must not be modified concurrently, but its writers take no common lock: `pci_set_master()` can run without the device lock (e.g. from runtime PM resume paths), `pci_disable_device()` clears the bit, and other bits in the same word are written from entirely different contexts, e.g. `broken_parity_status` from sysfs. Concurrent read-modify-write cycles of the shared word can then lose updates. Move `is_busmaster` into a new `flags` bitmap modified with atomic bitops and accessed through generated accessor functions, following the example of commit a7cc262a1135 ("driver core: Replace dev->offline + ->offline_disabled with accessors"). More bitfield flags can follow the same pattern later. This also unblocks the Rust device enabling API rework [1], where a guard object calls `pci_disable_device()` from contexts that may run concurrently with `pci_set_master()`. Link: https://lore.kernel.org/rust-for-linux/DJOEYVBS17MJ.1YD3TNGQBWHNK@kernel.org/ [1] Suggested-by: Danilo Krummrich Cc: rust-for-linux@vger.kernel.org Signed-off-by: Maurice Hieronymus --- drivers/net/ethernet/sfc/falcon/farch.c | 2 +- drivers/net/ethernet/sfc/siena/farch.c | 2 +- drivers/pci/pci-driver.c | 2 +- drivers/pci/pci.c | 6 ++--- drivers/scsi/lpfc/lpfc_init.c | 4 ++-- drivers/xen/xen-pciback/conf_space_header.c | 4 ++-- drivers/xen/xen-pciback/pciback_ops.c | 4 ++-- include/linux/pci.h | 37 ++++++++++++++++++++++++++++- 8 files changed, 48 insertions(+), 13 deletions(-) diff --git a/drivers/net/ethernet/sfc/falcon/farch.c b/drivers/net/ethernet/sfc/falcon/farch.c index 23d507a3820d..42594bd7e818 100644 --- a/drivers/net/ethernet/sfc/falcon/farch.c +++ b/drivers/net/ethernet/sfc/falcon/farch.c @@ -724,7 +724,7 @@ int ef4_farch_fini_dmaq(struct ef4_nic *efx) /* Do not attempt to write to the NIC during EEH recovery */ if (efx->state != STATE_RECOVERY) { /* Only perform flush if DMA is enabled */ - if (efx->pci_dev->is_busmaster) { + if (pci_dev_busmaster(efx->pci_dev)) { efx->type->prepare_flush(efx); rc = ef4_farch_do_flush(efx); efx->type->finish_flush(efx); diff --git a/drivers/net/ethernet/sfc/siena/farch.c b/drivers/net/ethernet/sfc/siena/farch.c index 7613d7988894..f673af4c77b6 100644 --- a/drivers/net/ethernet/sfc/siena/farch.c +++ b/drivers/net/ethernet/sfc/siena/farch.c @@ -723,7 +723,7 @@ int efx_farch_fini_dmaq(struct efx_nic *efx) /* Do not attempt to write to the NIC during EEH recovery */ if (efx->state != STATE_RECOVERY) { /* Only perform flush if DMA is enabled */ - if (efx->pci_dev->is_busmaster) { + if (pci_dev_busmaster(efx->pci_dev)) { efx->type->prepare_flush(efx); rc = efx_farch_do_flush(efx); efx->type->finish_flush(efx); diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index f36778e62ac1..412afa12a285 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -649,7 +649,7 @@ static int pci_pm_reenable_device(struct pci_dev *pci_dev) * if the device was busmaster before the suspend, make it busmaster * again */ - if (pci_dev->is_busmaster) + if (pci_dev_busmaster(pci_dev)) pci_set_master(pci_dev); return retval; diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 77b17b13ee61..c4fd6fe6098d 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2045,7 +2045,7 @@ static void pci_enable_bridge(struct pci_dev *dev) pci_enable_bridge(bridge); if (pci_is_enabled(dev)) { - if (!dev->is_busmaster) + if (!pci_dev_busmaster(dev)) pci_set_master(dev); return; } @@ -2205,7 +2205,7 @@ void pci_disable_device(struct pci_dev *dev) do_pci_disable_device(dev); - dev->is_busmaster = 0; + pci_dev_assign_busmaster(dev, false); } EXPORT_SYMBOL(pci_disable_device); @@ -4120,7 +4120,7 @@ static void __pci_set_master(struct pci_dev *dev, bool enable) enable ? "enabling" : "disabling"); pci_write_config_word(dev, PCI_COMMAND, cmd); } - dev->is_busmaster = enable; + pci_dev_assign_busmaster(dev, enable); } /** diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c index 82af59c913e9..08dc06e7dfc2 100644 --- a/drivers/scsi/lpfc/lpfc_init.c +++ b/drivers/scsi/lpfc/lpfc_init.c @@ -14398,7 +14398,7 @@ lpfc_io_slot_reset_s3(struct pci_dev *pdev) pci_restore_state(pdev); - if (pdev->is_busmaster) + if (pci_dev_busmaster(pdev)) pci_set_master(pdev); spin_lock_irq(&phba->hbalock); @@ -15251,7 +15251,7 @@ lpfc_io_slot_reset_s4(struct pci_dev *pdev) */ pci_save_state(pdev); - if (pdev->is_busmaster) + if (pci_dev_busmaster(pdev)) pci_set_master(pdev); spin_lock_irq(&phba->hbalock); diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c index 8b50cbcbdfe1..59a89f915916 100644 --- a/drivers/xen/xen-pciback/conf_space_header.c +++ b/drivers/xen/xen-pciback/conf_space_header.c @@ -81,10 +81,10 @@ static int command_write(struct pci_dev *dev, int offset, u16 value, void *data) dev_data->enable_intx = 0; } - if (!dev->is_busmaster && is_master_cmd(value)) { + if (!pci_dev_busmaster(dev) && is_master_cmd(value)) { dev_dbg(&dev->dev, "set bus master\n"); pci_set_master(dev); - } else if (dev->is_busmaster && !is_master_cmd(value)) { + } else if (pci_dev_busmaster(dev) && !is_master_cmd(value)) { dev_dbg(&dev->dev, "clear bus master\n"); pci_clear_master(dev); } diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c index bfc186bf05bc..01f4705421c9 100644 --- a/drivers/xen/xen-pciback/pciback_ops.c +++ b/drivers/xen/xen-pciback/pciback_ops.c @@ -125,14 +125,14 @@ void xen_pcibk_reset_device(struct pci_dev *dev) if (pci_is_enabled(dev)) pci_disable_device(dev); - dev->is_busmaster = 0; + pci_dev_assign_busmaster(dev, false); } else { pci_read_config_word(dev, PCI_COMMAND, &cmd); if (cmd & (PCI_COMMAND_INVALIDATE)) { cmd &= ~(PCI_COMMAND_INVALIDATE); pci_write_config_word(dev, PCI_COMMAND, cmd); - dev->is_busmaster = 0; + pci_dev_assign_busmaster(dev, false); } } } diff --git a/include/linux/pci.h b/include/linux/pci.h index ebb5b9d76360..9964646bdd46 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -336,6 +336,25 @@ struct pci_sriov; struct pci_p2pdma; struct rcec_ea; +/** + * enum struct_pci_dev_flags - Flags in struct pci_dev + * + * Each flag has a set of accessor functions created via + * __create_pci_dev_flag_accessors() and must only be accessed through + * them. + * + * @PCI_DEV_FLAG_BUSMASTER: Bus mastering is enabled on the device. Pure + * bookkeeping state, maintained by pci_set_master(), + * pci_clear_master() and pci_disable_device(); modifying it + * does not itself change the hardware state. + * @PCI_DEV_FLAG_COUNT: Number of defined struct_pci_dev_flags. + */ +enum struct_pci_dev_flags { + PCI_DEV_FLAG_BUSMASTER = 0, + + PCI_DEV_FLAG_COUNT +}; + /* struct pci_dev - describes a PCI device * * @supported_speeds: PCIe Supported Link Speeds Vector (+ reserved 0 at @@ -461,7 +480,6 @@ struct pci_dev { unsigned int pref_64_window:1; /* Pref mem window is 64-bit */ unsigned int multifunction:1; /* Multi-function device */ - unsigned int is_busmaster:1; /* Is busmaster */ unsigned int no_msi:1; /* May not use MSI */ unsigned int block_cfg_access:1; /* Config space access blocked */ unsigned int broken_parity_status:1; /* Generates false positive parity */ @@ -592,8 +610,25 @@ struct pci_dev { u8 tph_mode; /* TPH mode */ u8 tph_req_type; /* TPH requester type */ #endif + + /* PCI_DEV_FLAG_XXX flags. Use atomic bitfield operations to modify. */ + DECLARE_BITMAP(flags, PCI_DEV_FLAG_COUNT); }; +#define __create_pci_dev_flag_accessors(accessor_name, flag_name) \ +static inline bool pci_dev_##accessor_name(const struct pci_dev *pdev) \ +{ \ + return test_bit(flag_name, pdev->flags); \ +} \ +static inline void pci_dev_assign_##accessor_name(struct pci_dev *pdev, bool value) \ +{ \ + assign_bit(flag_name, pdev->flags, value); \ +} + +__create_pci_dev_flag_accessors(busmaster, PCI_DEV_FLAG_BUSMASTER); + +#undef __create_pci_dev_flag_accessors + static inline struct pci_dev *pci_physfn(struct pci_dev *dev) { #ifdef CONFIG_PCI_IOV -- 2.51.2