From: Andrew Morton <akpm@osdl.org>
To: James Nelson <james4765@verizon.net>
Cc: kernel-janitors@lists.osdl.org, linux-kernel@vger.kernel.org,
james4765@verizon.net
Subject: Re: [PATCH] esp: Make driver SMP-correct
Date: Fri, 31 Dec 2004 01:46:11 -0800 [thread overview]
Message-ID: <20041231014611.003281e5.akpm@osdl.org> (raw)
In-Reply-To: <20041231014403.3309.58245.96163@localhost.localdomain>
James Nelson <james4765@verizon.net> wrote:
>
> This is an attempt to make the esp serial driver SMP-correct. It also removes
> some cruft left over from the serial_write() conversion.
>From a quick scan:
- startup() does multiple sleeping allocations and request_irq() under
spin_lock_irqsave(). Maybe fixed by this:
--- 25/drivers/char/esp.c~esp-make-driver-smp-correct-fixes 2004-12-31 01:40:57.987232152 -0800
+++ 25-akpm/drivers/char/esp.c 2004-12-31 01:42:21.444544712 -0800
@@ -851,16 +851,14 @@ static int startup(struct esp_struct * i
int retval=0;
unsigned int num_chars;
- spin_lock_irqsave(&info->irq_lock, flags);
-
if (info->flags & ASYNC_INITIALIZED)
- goto out;
+ goto out_unlocked;
if (!info->xmit_buf) {
info->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
retval = -ENOMEM;
if (!info->xmit_buf)
- goto out;
+ goto out_unlocked;
}
#ifdef SERIAL_DEBUG_OPEN
@@ -907,7 +905,7 @@ static int startup(struct esp_struct * i
&info->tty->flags);
retval = 0;
}
- goto out;
+ goto out_unocked;
}
if (!(info->stat_flags & ESP_STAT_USE_PIO) && !dma_buffer) {
@@ -926,6 +924,8 @@ static int startup(struct esp_struct * i
}
+ spin_lock_irqsave(&info->irq_lock, flags);
+
info->MCR = UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2;
serial_out(info, UART_ESI_CMD1, ESI_WRITE_UART);
serial_out(info, UART_ESI_CMD2, UART_MCR);
@@ -965,7 +965,9 @@ static int startup(struct esp_struct * i
info->flags |= ASYNC_INITIALIZED;
retval = 0;
-out: spin_unlock_irqrestore(&info->irq_lock, flags);
+out:
+ spin_unlock_irqrestore(&info->irq_lock, flags);
+out_unocked:
return retval;
}
_
- startup() calls change_speed() under info->irq_lock, but change_speed()
also takes info->irq_lock. Instant deadlock on driver initialisation.
The driver needs more serious surgery than this.
next prev parent reply other threads:[~2004-12-31 9:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-31 1:43 [PATCH] esp: Make driver SMP-correct James Nelson
2004-12-31 9:45 ` Jan Dittmer
2004-12-31 9:46 ` Andrew Morton [this message]
2004-12-31 10:00 ` Russell King
2004-12-31 11:00 ` Jim Nelson
2004-12-31 17:01 ` Russell King
2004-12-31 22:16 ` [KJ] " Jim Nelson
2005-01-01 0:01 ` Gene Heskett
2005-01-01 0:13 ` Russell King
2005-01-01 1:14 ` Gene Heskett
2005-01-01 1:33 ` Russell King
2005-01-01 1:49 ` Jim Nelson
2005-01-01 1:35 ` Gene Heskett
2005-01-01 1:47 ` Jim Nelson
2005-01-01 3:11 ` Gene Heskett
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