Messages in this thread Patch in this message | | | Date | Thu, 01 Oct 2009 15:59:54 -0400 | From | Douglas Gilbert <> | Subject | Re: [BUG] sg.c: sleeping function called from invalid context |
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iceberg wrote: > KERNEL_VERSION: 2.6.31 > DESCRIBE: > Driver sg.c might sleep in atomic context, because it calls > scsi_device_put under lock_kernel. > > /drivers/scsi/sg.c:306: > static int > sg_open(struct inode *inode, struct file *filp) > { > ... > lock_kernel(); > ... > error_out: > if (retval) > scsi_device_put(sdp->device); > ... > > Path to might_sleep macro from scsi_device_put: > 1. scsi_device_put calls put_device at ./drivers/scsi/scsi.c:1111 > 2. put_device calls kobject_put at ./drivers/base/core.c:1038 > 3. kobject_put calls kref_put at ./lib/kobject.c > 4. kref_put may call callback function kobject_release at ./lib/kref.c if > refcount becomes zero, which might_sleep because it calls user event. Details: > 5.1 kobject_cleanup calls kobject_uevent at ./lib/kobject.c:555 > 5.2 kobject_uevent calls kobject_uevent_env at ./lib/kobject_uevent.c:282 > 5.3 kobject_uevent_env calls call_usermodehelper_exec at > include/linux/kmod.h:83 > 5.4 call_usermodehelper_exec calls wait_for_completion at ./kernel/kmod.c:481 > 5.5 wait_for_completion calls wait_for_common at ./kernel/sched.c:5710 > 5.6 wait_for_common calls might_sleep at ./kernels/sched.c:5692 > > Found by: Linux Driver Verification
This patch to sg_open() does one (and only one) unlock_kernel() prior to scsi_device_put(). I presume sg_put_dev() may also sleep so the unlock_kernel() is moved before it as well.
Hopefully Tomo will comment.
Doug Gilbert
--- linux/drivers/scsi/sg.c2631 2009-09-10 06:22:34.000000000 -0400 +++ linux/drivers/scsi/sg.c 2009-10-01 15:54:30.000000000 -0400 @@ -227,8 +227,10 @@ Sg_fd *sfp; int res; int retval; + int locked = 0;
lock_kernel(); + locked = 1; nonseekable_open(inode, filp); SCSI_LOG_TIMEOUT(3, printk("sg_open: dev=%d, flags=0x%x\n", dev, flags)); sdp = sg_get_dev(dev); @@ -302,12 +304,16 @@ } retval = 0; error_out: - if (retval) + if (retval) { + unlock_kernel(); + locked = 0; scsi_device_put(sdp->device); + } sg_put: + if (locked) + unlock_kernel(); if (sdp) sg_put_dev(sdp); - unlock_kernel(); return retval; }
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