Messages in this thread | | | Date | Thu, 09 Nov 2000 14:27:01 -0500 | From | Brian Gerst <> | Subject | Re: Module open() problems, Linux 2.4.0 |
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"Richard B. Johnson" wrote: > > `lsmod` shows that a device is open twice when using Linux-2.4.0-test9 > when, in fact, it has been opened only once. > > lsmod is version 2.3.15, the latest-and-greatest. > > Here are the open/close routines for a module. > > /*-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=*/ > /* > * Open the device. > */ > static int device_open(struct inode *inp, struct file *fp) > { > DEB(printk("%s open\n", info->dev)); > MOD_INC_USE_COUNT; /* Increment usage count */ > return 0; > } > /*-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=*/ > /* > * Close the device. > */ > static int device_close(struct inode *inp, struct file *fp) > { > DEB(printk("%s close\n", info->dev)); > MOD_DEC_USE_COUNT; /* Decrement usage count */ > return 0; > } > > When the module is closed, the use-count goes to zero as expected. > However, a single open() causes the use-count to be 2.
This is harmless. It is caused by a try_inc_mod_count(module) in the function calling device_open(), which is the proper way for module locking to be handled when not holding the BKL. You can keep the MOD_INC_USE_COUNT in the device driver for compatability with 2.2.
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