From d21c95c569c462da20d491b75d0a45bd70ddc1bf Mon Sep 17 00:00:00 2001 From: Jonathan Corbet Date: Fri, 16 May 2008 13:40:30 -0600 Subject: Add "no BKL needed" comments to several drivers This documents the fact that somebody looked at the relevant open() functions and concluded that, due to their trivial nature, no locking was needed. Signed-off-by: Jonathan Corbet --- drivers/infiniband/core/ucm.c | 1 + drivers/infiniband/hw/ipath/ipath_file_ops.c | 1 + 2 files changed, 2 insertions(+) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c index d7a6881b571d..3e6a8ff6d76c 100644 --- a/drivers/infiniband/core/ucm.c +++ b/drivers/infiniband/core/ucm.c @@ -1155,6 +1155,7 @@ static unsigned int ib_ucm_poll(struct file *filp, return mask; } +/* No BKL needed here: no global resources used */ static int ib_ucm_open(struct inode *inode, struct file *filp) { struct ib_ucm_file *file; diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c index b472b15637f0..e80cfbd4f3fd 100644 --- a/drivers/infiniband/hw/ipath/ipath_file_ops.c +++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c @@ -1812,6 +1812,7 @@ done: return ret; } +/* No BKL needed here */ static int ipath_open(struct inode *in, struct file *fp) { /* The real work is performed later in ipath_assign_port() */ -- cgit v1.2.3 From 057e7c7ff9f91a36a761588c53826bd6a710aeba Mon Sep 17 00:00:00 2001 From: Jonathan Corbet Date: Fri, 16 May 2008 14:01:12 -0600 Subject: infiniband: more BKL pushdown Be extra-cautious and protect the remaining open() functions. Signed-off-by: Jonathan Corbet --- drivers/infiniband/core/user_mad.c | 7 ++++++- drivers/infiniband/core/uverbs_main.c | 9 +++++++-- 2 files changed, 13 insertions(+), 3 deletions(-) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c index 3aa2db54eae4..1fc17940a765 100644 --- a/drivers/infiniband/core/user_mad.c +++ b/drivers/infiniband/core/user_mad.c @@ -47,6 +47,7 @@ #include #include #include +#include #include @@ -783,14 +784,17 @@ static int ib_umad_open(struct inode *inode, struct file *filp) struct ib_umad_file *file; int ret = 0; + lock_kernel(); spin_lock(&port_lock); port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE]; if (port) kref_get(&port->umad_dev->ref); spin_unlock(&port_lock); - if (!port) + if (!port) { + unlock_kernel(); return -ENXIO; + } mutex_lock(&port->file_mutex); @@ -819,6 +823,7 @@ static int ib_umad_open(struct inode *inode, struct file *filp) out: mutex_unlock(&port->file_mutex); + unlock_kernel(); return ret; } diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index cc1afa28c181..8ede1e475ce6 100644 --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -45,6 +45,7 @@ #include #include #include +#include #include @@ -616,14 +617,17 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp) struct ib_uverbs_file *file; int ret; + lock_kernel(); spin_lock(&map_lock); dev = dev_table[iminor(inode) - IB_UVERBS_BASE_MINOR]; if (dev) kref_get(&dev->ref); spin_unlock(&map_lock); - if (!dev) + if (!dev) { + unlock_kernel(); return -ENXIO; + } if (!try_module_get(dev->ib_dev->owner)) { ret = -ENODEV; @@ -644,6 +648,7 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp) filp->private_data = file; + unlock_kernel(); return 0; err_module: @@ -651,7 +656,7 @@ err_module: err: kref_put(&dev->ref, ib_uverbs_release_dev); - + unlock_kernel(); return ret; } -- cgit v1.2.3 From f2b9857eee17797541b845782ade4d7a9d50f843 Mon Sep 17 00:00:00 2001 From: Jonathan Corbet Date: Sun, 18 May 2008 15:32:43 -0600 Subject: Add a bunch of cycle_kernel_lock() calls All of the open() functions which don't need the BKL on their face may still depend on its acquisition to serialize opens against driver initialization. So make those functions acquire then release the BKL to be on the safe side. Signed-off-by: Jonathan Corbet --- arch/cris/arch-v10/drivers/eeprom.c | 4 ++-- arch/cris/arch-v10/drivers/i2c.c | 2 ++ arch/cris/arch-v32/drivers/cryptocop.c | 3 ++- arch/cris/arch-v32/drivers/i2c.c | 2 ++ drivers/char/cs5535_gpio.c | 4 ++-- drivers/char/dtlk.c | 5 ++-- drivers/char/ip2/ip2main.c | 34 ++-------------------------- drivers/char/pc8736x_gpio.c | 3 ++- drivers/char/ppdev.c | 3 ++- drivers/char/scx200_gpio.c | 3 ++- drivers/char/tb0219.c | 3 ++- drivers/char/vr41xx_giu.c | 4 ++-- drivers/infiniband/core/ucm.c | 3 ++- drivers/infiniband/hw/ipath/ipath_file_ops.c | 3 ++- drivers/isdn/hardware/eicon/divasi.c | 2 ++ drivers/isdn/hardware/eicon/divasmain.c | 2 ++ drivers/net/ppp_generic.c | 3 ++- drivers/scsi/3w-9xxx.c | 5 ++-- drivers/scsi/3w-xxxx.c | 5 ++-- drivers/scsi/megaraid.c | 4 ++-- drivers/scsi/megaraid/megaraid_sas.c | 3 ++- 21 files changed, 45 insertions(+), 55 deletions(-) (limited to 'drivers/infiniband') diff --git a/arch/cris/arch-v10/drivers/eeprom.c b/arch/cris/arch-v10/drivers/eeprom.c index 40c6fe4c06f4..1f2ae909d3e6 100644 --- a/arch/cris/arch-v10/drivers/eeprom.c +++ b/arch/cris/arch-v10/drivers/eeprom.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include "i2c.h" @@ -375,10 +376,9 @@ int __init eeprom_init(void) } /* Opens the device. */ -/* BKL not needed: no global resources accessed */ static int eeprom_open(struct inode * inode, struct file * file) { - + cycle_kernel_lock(); if(iminor(inode) != EEPROM_MINOR_NR) return -ENXIO; if(imajor(inode) != EEPROM_MAJOR_NR) diff --git a/arch/cris/arch-v10/drivers/i2c.c b/arch/cris/arch-v10/drivers/i2c.c index d6d22067d0c8..2797e67ce4f4 100644 --- a/arch/cris/arch-v10/drivers/i2c.c +++ b/arch/cris/arch-v10/drivers/i2c.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -566,6 +567,7 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg) static int i2c_open(struct inode *inode, struct file *filp) { + cycle_kernel_lock(); return 0; } diff --git a/arch/cris/arch-v32/drivers/cryptocop.c b/arch/cris/arch-v32/drivers/cryptocop.c index c17204289575..67c61ea86813 100644 --- a/arch/cris/arch-v32/drivers/cryptocop.c +++ b/arch/cris/arch-v32/drivers/cryptocop.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -2302,11 +2303,11 @@ static int cryptocop_job_setup(struct cryptocop_prio_job **pj, struct cryptocop_ return 0; } -/* No BKL needed here - no global resources accessed */ static int cryptocop_open(struct inode *inode, struct file *filp) { int p = iminor(inode); + cycle_kernel_lock(); if (p != CRYPTOCOP_MINOR) return -EINVAL; filp->private_data = NULL; diff --git a/arch/cris/arch-v32/drivers/i2c.c b/arch/cris/arch-v32/drivers/i2c.c index c2fb7a5c1396..179e7b804331 100644 --- a/arch/cris/arch-v32/drivers/i2c.c +++ b/arch/cris/arch-v32/drivers/i2c.c @@ -33,6 +33,7 @@ #include #include #include +#include #include @@ -636,6 +637,7 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg) static int i2c_open(struct inode *inode, struct file *filp) { + cycle_kernel_lock(); return 0; } diff --git a/drivers/char/cs5535_gpio.c b/drivers/char/cs5535_gpio.c index 628e3d3249d2..04ba906b4880 100644 --- a/drivers/char/cs5535_gpio.c +++ b/drivers/char/cs5535_gpio.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -153,12 +154,11 @@ static ssize_t cs5535_gpio_read(struct file *file, char __user *buf, return count; } -/* No BKL needed here - "mask" is the only global resource used - here and it's a boot-time parameter */ static int cs5535_gpio_open(struct inode *inode, struct file *file) { u32 m = iminor(inode); + cycle_kernel_lock(); /* the mask says which pins are usable by this driver */ if ((mask & (1 << m)) == 0) return -EINVAL; diff --git a/drivers/char/dtlk.c b/drivers/char/dtlk.c index 433388c60235..6b900b297cc6 100644 --- a/drivers/char/dtlk.c +++ b/drivers/char/dtlk.c @@ -56,6 +56,7 @@ #include /* for -EBUSY */ #include /* for request_region */ #include /* for loops_per_jiffy */ +#include /* cycle_kernel_lock() */ #include /* for inb_p, outb_p, inb, outb, etc. */ #include /* for get_user, etc. */ #include /* for wait_queue */ @@ -288,12 +289,12 @@ static int dtlk_ioctl(struct inode *inode, } } -/* No BKL needed here; "dtlk_busy" is the only global resource, - and it is not ever set by anybody (test is broken) */ +/* Note that nobody ever sets dtlk_busy... */ static int dtlk_open(struct inode *inode, struct file *file) { TRACE_TEXT("(dtlk_open"); + cycle_kernel_lock(); nonseekable_open(inode, file); switch (iminor(inode)) { case DTLK_MINOR: diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c index 70957acaa960..a978c57b6b2b 100644 --- a/drivers/char/ip2/ip2main.c +++ b/drivers/char/ip2/ip2main.c @@ -98,6 +98,7 @@ #include #include #include +#include #include #include @@ -2931,42 +2932,11 @@ ip2_ipl_ioctl ( struct inode *pInode, struct file *pFile, UINT cmd, ULONG arg ) static int ip2_ipl_open( struct inode *pInode, struct file *pFile ) { - unsigned int iplminor = iminor(pInode); - i2eBordStrPtr pB; - i2ChanStrPtr pCh; #ifdef IP2DEBUG_IPL printk (KERN_DEBUG "IP2IPL: open\n" ); #endif - - switch(iplminor) { - // These are the IPL devices - case 0: - case 4: - case 8: - case 12: - break; - - // These are the status devices - case 1: - case 5: - case 9: - case 13: - break; - - // These are the debug devices - case 2: - case 6: - case 10: - case 14: - pB = i2BoardPtrTable[iplminor / 4]; - pCh = (i2ChanStrPtr) pB->i2eChannelPtr; - break; - - // This is the trace device - case 3: - break; - } + cycle_kernel_lock(); return 0; } diff --git a/drivers/char/pc8736x_gpio.c b/drivers/char/pc8736x_gpio.c index 8715dc9f4a53..b930de50407a 100644 --- a/drivers/char/pc8736x_gpio.c +++ b/drivers/char/pc8736x_gpio.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #define DEVNAME "pc8736x_gpio" @@ -212,12 +213,12 @@ static struct nsc_gpio_ops pc8736x_gpio_ops = { .gpio_current = pc8736x_gpio_current }; -/* No BKL needed here; no global resources accessed */ static int pc8736x_gpio_open(struct inode *inode, struct file *file) { unsigned m = iminor(inode); file->private_data = &pc8736x_gpio_ops; + cycle_kernel_lock(); dev_dbg(&pdev->dev, "open %d\n", m); if (m >= PC8736X_GPIO_CT) diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c index ce1987574888..f6e6acadd9a0 100644 --- a/drivers/char/ppdev.c +++ b/drivers/char/ppdev.c @@ -66,6 +66,7 @@ #include #include #include +#include #include #define PP_VERSION "ppdev: user-space parallel port driver" @@ -633,12 +634,12 @@ static int pp_ioctl(struct inode *inode, struct file *file, return 0; } -/* No BKL needed here: only local resources used */ static int pp_open (struct inode * inode, struct file * file) { unsigned int minor = iminor(inode); struct pp_struct *pp; + cycle_kernel_lock(); if (minor >= PARPORT_MAX) return -ENXIO; diff --git a/drivers/char/scx200_gpio.c b/drivers/char/scx200_gpio.c index be2c623a9862..1d9100561c8a 100644 --- a/drivers/char/scx200_gpio.c +++ b/drivers/char/scx200_gpio.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include @@ -46,12 +47,12 @@ struct nsc_gpio_ops scx200_gpio_ops = { }; EXPORT_SYMBOL_GPL(scx200_gpio_ops); -/* No BKL needed here: no global resources used */ static int scx200_gpio_open(struct inode *inode, struct file *file) { unsigned m = iminor(inode); file->private_data = &scx200_gpio_ops; + cycle_kernel_lock(); if (m >= MAX_PINS) return -EINVAL; return nonseekable_open(inode, file); diff --git a/drivers/char/tb0219.c b/drivers/char/tb0219.c index db8c2ca2ce4c..6062b62800fd 100644 --- a/drivers/char/tb0219.c +++ b/drivers/char/tb0219.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -232,11 +233,11 @@ static ssize_t tanbac_tb0219_write(struct file *file, const char __user *data, return i; } -/* No BKL needed here; no global resources accessed */ static int tanbac_tb0219_open(struct inode *inode, struct file *file) { unsigned int minor; + cycle_kernel_lock(); minor = iminor(inode); switch (minor) { case 0: diff --git a/drivers/char/vr41xx_giu.c b/drivers/char/vr41xx_giu.c index 412937fdb958..ffe9b4e3072e 100644 --- a/drivers/char/vr41xx_giu.c +++ b/drivers/char/vr41xx_giu.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include @@ -543,12 +544,11 @@ static ssize_t gpio_write(struct file *file, const char __user *data, return i; } -/* No BKL needed here; only global (giu_nr_pins) is only set - at probe time */ static int gpio_open(struct inode *inode, struct file *file) { unsigned int pin; + cycle_kernel_lock(); pin = iminor(inode); if (pin >= giu_nr_pins) return -EBADF; diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c index 3e6a8ff6d76c..b25675faaaf5 100644 --- a/drivers/infiniband/core/ucm.c +++ b/drivers/infiniband/core/ucm.c @@ -45,6 +45,7 @@ #include #include #include +#include #include @@ -1155,11 +1156,11 @@ static unsigned int ib_ucm_poll(struct file *filp, return mask; } -/* No BKL needed here: no global resources used */ static int ib_ucm_open(struct inode *inode, struct file *filp) { struct ib_ucm_file *file; + cycle_kernel_lock(); file = kmalloc(sizeof(*file), GFP_KERNEL); if (!file) return -ENOMEM; diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c index e80cfbd4f3fd..35f301c88b57 100644 --- a/drivers/infiniband/hw/ipath/ipath_file_ops.c +++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include "ipath_kernel.h" @@ -1812,10 +1813,10 @@ done: return ret; } -/* No BKL needed here */ static int ipath_open(struct inode *in, struct file *fp) { /* The real work is performed later in ipath_assign_port() */ + cycle_kernel_lock(); fp->private_data = kzalloc(sizeof(struct ipath_filedata), GFP_KERNEL); return fp->private_data ? 0 : -ENOMEM; } diff --git a/drivers/isdn/hardware/eicon/divasi.c b/drivers/isdn/hardware/eicon/divasi.c index 78f141e77466..f4969fe0a055 100644 --- a/drivers/isdn/hardware/eicon/divasi.c +++ b/drivers/isdn/hardware/eicon/divasi.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include "platform.h" @@ -400,6 +401,7 @@ static unsigned int um_idi_poll(struct file *file, poll_table * wait) static int um_idi_open(struct inode *inode, struct file *file) { + cycle_kernel_lock(); return (0); } diff --git a/drivers/isdn/hardware/eicon/divasmain.c b/drivers/isdn/hardware/eicon/divasmain.c index 5fcbdccd7a53..65c95019a9ae 100644 --- a/drivers/isdn/hardware/eicon/divasmain.c +++ b/drivers/isdn/hardware/eicon/divasmain.c @@ -21,6 +21,7 @@ #include #include #include +#include #include "platform.h" #undef ID_MASK @@ -580,6 +581,7 @@ xdi_copy_from_user(void *os_handle, void *dst, const void __user *src, int lengt */ static int divas_open(struct inode *inode, struct file *file) { + cycle_kernel_lock(); return (0); } diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c index dc8505062da7..83625fdff3dd 100644 --- a/drivers/net/ppp_generic.c +++ b/drivers/net/ppp_generic.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include #include @@ -351,9 +352,9 @@ static const int npindex_to_ethertype[NUM_NP] = { * Open instances of /dev/ppp can be in one of three states: * unattached, attached to a ppp unit, or attached to a ppp channel. */ -/* No BKL needed here */ static int ppp_open(struct inode *inode, struct file *file) { + cycle_kernel_lock(); /* * This could (should?) be enforced by the permissions on /dev/ppp. */ diff --git a/drivers/scsi/3w-9xxx.c b/drivers/scsi/3w-9xxx.c index 2239d16fb9b5..eaa805df5b00 100644 --- a/drivers/scsi/3w-9xxx.c +++ b/drivers/scsi/3w-9xxx.c @@ -84,6 +84,7 @@ #include #include #include +#include #include #include #include @@ -862,13 +863,13 @@ out: } /* End twa_chrdev_ioctl() */ /* This function handles open for the character device */ -/* NOTE that this function will race with remove; adding BKL - will not help. */ +/* NOTE that this function will race with remove. */ static int twa_chrdev_open(struct inode *inode, struct file *file) { unsigned int minor_number; int retval = TW_IOCTL_ERROR_OS_ENODEV; + cycle_kernel_lock(); minor_number = iminor(inode); if (minor_number >= twa_device_extension_count) goto out; diff --git a/drivers/scsi/3w-xxxx.c b/drivers/scsi/3w-xxxx.c index bbff029536ea..a0537f09aa21 100644 --- a/drivers/scsi/3w-xxxx.c +++ b/drivers/scsi/3w-xxxx.c @@ -198,6 +198,7 @@ #include #include +#include #include #include #include @@ -1027,12 +1028,12 @@ out: } /* End tw_chrdev_ioctl() */ /* This function handles open for the character device */ -/* NOTE that this function races with remove - adding BKL - won't help */ +/* NOTE that this function races with remove. */ static int tw_chrdev_open(struct inode *inode, struct file *file) { unsigned int minor_number; + cycle_kernel_lock(); dprintk(KERN_WARNING "3w-xxxx: tw_ioctl_open()\n"); minor_number = iminor(inode); diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c index c9aa2c45a699..28c9da7d4a5c 100644 --- a/drivers/scsi/megaraid.c +++ b/drivers/scsi/megaraid.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include "scsi.h" @@ -3273,12 +3274,11 @@ mega_init_scb(adapter_t *adapter) * * Routines for the character/ioctl interface to the driver. Find out if this * is a valid open. - * - * No BKL needed here. */ static int megadev_open (struct inode *inode, struct file *filep) { + cycle_kernel_lock(); /* * Only allow superuser to access private ioctl interface */ diff --git a/drivers/scsi/megaraid/megaraid_sas.c b/drivers/scsi/megaraid/megaraid_sas.c index 81374b7c555c..fc7ac158476c 100644 --- a/drivers/scsi/megaraid/megaraid_sas.c +++ b/drivers/scsi/megaraid/megaraid_sas.c @@ -33,6 +33,7 @@ #include #include #include +#include #include #include #include @@ -2860,10 +2861,10 @@ static void megasas_shutdown(struct pci_dev *pdev) /** * megasas_mgmt_open - char node "open" entry point - * No BKL is needed here. */ static int megasas_mgmt_open(struct inode *inode, struct file *filep) { + cycle_kernel_lock(); /* * Allow only those users with admin rights */ -- cgit v1.2.3 From 6b0ee363b294c3724224909dcb0b80f7dac3dfd6 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 20 May 2008 19:16:02 +0200 Subject: infiniband-ucma: BKL pushdown Signed-off-by: Arnd Bergmann --- drivers/infiniband/core/ucma.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index ca4cf3a511ab..195f97302fe5 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include @@ -1156,6 +1157,7 @@ static int ucma_open(struct inode *inode, struct file *filp) if (!file) return -ENOMEM; + lock_kernel(); INIT_LIST_HEAD(&file->event_list); INIT_LIST_HEAD(&file->ctx_list); init_waitqueue_head(&file->poll_wait); @@ -1163,6 +1165,7 @@ static int ucma_open(struct inode *inode, struct file *filp) filp->private_data = file; file->filp = filp; + unlock_kernel(); return 0; } -- cgit v1.2.3 From 5b2d281acb04a29fcdc76ced5ca6099565a0747f Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Fri, 27 Jun 2008 14:43:20 -0700 Subject: IB/uverbs: BKL is not needed for ib_uverbs_open() Remove explicit lock_kernel() calls and document why the code is safe. Signed-off-by: Roland Dreier Signed-off-by: Jonathan Corbet --- drivers/infiniband/core/uverbs_main.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index 8ede1e475ce6..fdfcf7910d9a 100644 --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -45,7 +45,6 @@ #include #include #include -#include #include @@ -611,23 +610,32 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma) return file->device->ib_dev->mmap(file->ucontext, vma); } +/* + * ib_uverbs_open() does not need the BKL: + * + * - dev_table[] accesses are protected by map_lock, the + * ib_uverbs_device structures are properly reference counted, and + * everything else is purely local to the file being created, so + * races against other open calls are not a problem; + * - there is no ioctl method to race against; + * - the device is added to dev_table[] as the last part of module + * initialization, the open method will either immediately run + * -ENXIO, or all required initialization will be done. + */ static int ib_uverbs_open(struct inode *inode, struct file *filp) { struct ib_uverbs_device *dev; struct ib_uverbs_file *file; int ret; - lock_kernel(); spin_lock(&map_lock); dev = dev_table[iminor(inode) - IB_UVERBS_BASE_MINOR]; if (dev) kref_get(&dev->ref); spin_unlock(&map_lock); - if (!dev) { - unlock_kernel(); + if (!dev) return -ENXIO; - } if (!try_module_get(dev->ib_dev->owner)) { ret = -ENODEV; @@ -648,7 +656,6 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp) filp->private_data = file; - unlock_kernel(); return 0; err_module: @@ -656,7 +663,6 @@ err_module: err: kref_put(&dev->ref, ib_uverbs_release_dev); - unlock_kernel(); return ret; } -- cgit v1.2.3 From feae1ef116ed381625d3731c5ae4f4ebcb3fa302 Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Fri, 11 Jul 2008 13:54:40 -0700 Subject: IB/umad: BKL is not needed for ib_umad_open() Remove explicit lock_kernel() calls and document why the code is safe. Signed-off-by: Roland Dreier Signed-off-by: Jonathan Corbet --- drivers/infiniband/core/user_mad.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c index 1fc17940a765..ef6dd825fee9 100644 --- a/drivers/infiniband/core/user_mad.c +++ b/drivers/infiniband/core/user_mad.c @@ -47,7 +47,6 @@ #include #include #include -#include #include @@ -778,23 +777,33 @@ static long ib_umad_compat_ioctl(struct file *filp, unsigned int cmd, } #endif +/* + * ib_umad_open() does not need the BKL: + * + * - umad_port[] accesses are protected by port_lock, the + * ib_umad_port structures are properly reference counted, and + * everything else is purely local to the file being created, so + * races against other open calls are not a problem; + * - the ioctl method does not affect any global state outside of the + * file structure being operated on; + * - the port is added to umad_port[] as the last part of module + * initialization so the open method will either immediately run + * -ENXIO, or all required initialization will be done. + */ static int ib_umad_open(struct inode *inode, struct file *filp) { struct ib_umad_port *port; struct ib_umad_file *file; int ret = 0; - lock_kernel(); spin_lock(&port_lock); port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE]; if (port) kref_get(&port->umad_dev->ref); spin_unlock(&port_lock); - if (!port) { - unlock_kernel(); + if (!port) return -ENXIO; - } mutex_lock(&port->file_mutex); @@ -823,7 +832,6 @@ static int ib_umad_open(struct inode *inode, struct file *filp) out: mutex_unlock(&port->file_mutex); - unlock_kernel(); return ret; } -- cgit v1.2.3