Re: alpha fp-emu vs module refcounting

Ivan Kokshaysky
2004-05-07T14:32:43Z

On Fri, May 07, 2004 at 01:02:17PM +0200, Christoph Hellwig wrote:
> any chance we could either do a try_module_get on a struct module
> *fp_emul_module in alpha core code before or completely disallow module
> unloading for it (by removing the cleanup_module() callback)?

How about this (also fixes modular build of math-emu)?

Ivan.

--- 2.6/arch/alpha/math-emu/math.c Sun Apr 4 07:38:23 2004
+++ linux/arch/alpha/math-emu/math.c Fri May 7 18:21:15 2004
@@ -51,7 +51,9 @@ extern void alpha_write_fp_reg_s (unsign

#ifdef MODULE

+MODULE_AUTHOR("Richard Henderson <rth@twiddle.net>");
MODULE_DESCRIPTION("FP Software completion module");
+MODULE_LICENSE("GPL");

extern long (*alpha_fp_emul_imprecise)(struct pt_regs *, unsigned long);
extern long (*alpha_fp_emul) (unsigned long pc);
@@ -106,7 +108,7 @@ alpha_fp_emul (unsigned long pc)
__u32 insn;
long si_code;

- MOD_INC_USE_COUNT;
+ BUG_ON(!try_module_get(THIS_MODULE));

get_user(insn, (__u32*)pc);
fc = (insn >> 0) & 0x1f; /* destination register */
@@ -320,7 +322,7 @@ done:
if (_fex & IEEE_TRAP_ENABLE_INV) si_code = FPE_FLTINV;
}

- MOD_DEC_USE_COUNT;
+ module_put(THIS_MODULE);
return si_code;
}

@@ -328,13 +330,13 @@ done:
requires that the result *always* be written... so we do the write
immediately after the operations above. */

- MOD_DEC_USE_COUNT;
+ module_put(THIS_MODULE);
return 0;

bad_insn:
printk(KERN_ERR "alpha_fp_emul: Invalid FP insn %#x at %#lx\n",
insn, pc);
- MOD_DEC_USE_COUNT;
+ module_put(THIS_MODULE);
return -1;
}

@@ -344,7 +346,7 @@ alpha_fp_emul_imprecise (struct pt_regs
unsigned long trigger_pc = regs->pc - 4;
unsigned long insn, opcode, rc, si_code = 0;

- MOD_INC_USE_COUNT;
+ BUG_ON(!try_module_get(THIS_MODULE));

/*
* Turn off the bits corresponding to registers that are the
@@ -403,6 +405,6 @@ alpha_fp_emul_imprecise (struct pt_regs
}

egress:
- MOD_DEC_USE_COUNT;
+ module_put(THIS_MODULE);
return si_code;
}
--- 2.6/arch/alpha/math-emu/Makefile Sun Apr 4 07:37:23 2004
+++ linux/arch/alpha/math-emu/Makefile Fri May 7 17:52:22 2004
@@ -4,4 +4,6 @@

EXTRA_CFLAGS := -w

-obj-$(CONFIG_MATHEMU) += math.o qrnnd.o
+obj-$(CONFIG_MATHEMU) += math-emu.o
+
+math-emu-objs := math.o qrnnd.o