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Linux driver: Protect recv and send with atomic test and set instead of lock to enable clear at reset

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This commit is contained in:
Adrien Prost-Boucle 2016-01-06 17:34:41 +01:00
parent 3775133808
commit 9f791acfea
1 changed files with 13 additions and 10 deletions
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23
driver/linux/riffa_driver.c
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@ -53,7 +53,6 @@
#include <linux/interrupt.h> #include <linux/interrupt.h>
#include <linux/sched.h> #include <linux/sched.h>
#include <linux/rwsem.h> #include <linux/rwsem.h>
#include <linux/semaphore.h>
#include <linux/dma-mapping.h> #include <linux/dma-mapping.h>
#include <linux/pagemap.h> #include <linux/pagemap.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
@ -76,6 +75,8 @@ MODULE_AUTHOR("Matt Jacobsen, Patrick Lai");
#define BUILD_32 1 #define BUILD_32 1
#endif #endif
#define CHNL_FLAG_BUSY 0
struct sg_mapping { struct sg_mapping {
struct page ** pages; struct page ** pages;
struct scatterlist * sgl; struct scatterlist * sgl;
@ -87,7 +88,7 @@ struct sg_mapping {
}; };
struct chnl_dir { struct chnl_dir {
struct semaphore sem; volatile unsigned long flags;
wait_queue_head_t waitq; wait_queue_head_t waitq;
struct circ_queue * msgs; struct circ_queue * msgs;
void * buf_addr; void * buf_addr;
@ -686,15 +687,15 @@ static inline unsigned int chnl_recv_wrapcheck(struct fpga_state * sc, int chnl,
} }
// Ensure no simultaneous operations from several threads // Ensure no simultaneous operations from several threads
if (down_trylock(&sc->recv[chnl]->sem) != 0) { if (test_and_set_bit(CHNL_FLAG_BUSY, &sc->recv[chnl]->flags) != 0) {
printk(KERN_ERR "riffa: fpga:%d chnl:%d, recv conflict between threads!\n", sc->id, chnl); printk(KERN_ERR "riffa: fpga:%d chnl:%d, recv conflict between threads!\n", sc->id, chnl);
return -EBUSY; return -EBUSY;
} }
ret = chnl_recv(sc, chnl, bufp, len, timeout); ret = chnl_recv(sc, chnl, bufp, len, timeout);
// Release the semaphore // Clear the busy flag
up(&sc->recv[chnl]->sem); clear_bit(CHNL_FLAG_BUSY, &sc->recv[chnl]->flags);
return ret; return ret;
} }
@ -856,15 +857,15 @@ static inline unsigned int chnl_send_wrapcheck(struct fpga_state * sc, int chnl,
} }
// Ensure no simultaneous operations from several threads // Ensure no simultaneous operations from several threads
if (down_trylock(&sc->send[chnl]->sem) != 0) { if (test_and_set_bit(CHNL_FLAG_BUSY, &sc->send[chnl]->flags) != 0) {
printk(KERN_ERR "riffa: fpga:%d chnl:%d, send conflict between threads!\n", sc->id, chnl); printk(KERN_ERR "riffa: fpga:%d chnl:%d, send conflict between threads!\n", sc->id, chnl);
return -EBUSY; return -EBUSY;
} }
ret = chnl_send(sc, chnl, bufp, len, offset, last, timeout); ret = chnl_send(sc, chnl, bufp, len, offset, last, timeout);
// Release the semaphore // Clear the busy flag
up(&sc->send[chnl]->sem); clear_bit(CHNL_FLAG_BUSY, &sc->send[chnl]->flags);
return ret; return ret;
} }
@ -927,6 +928,8 @@ static inline void reset(int id)
while (!pop_circ_queue(sc->recv[i]->msgs, &dummy0, &dummy1)); while (!pop_circ_queue(sc->recv[i]->msgs, &dummy0, &dummy1));
wake_up(&sc->send[i]->waitq); wake_up(&sc->send[i]->waitq);
wake_up(&sc->recv[i]->waitq); wake_up(&sc->recv[i]->waitq);
clear_bit(CHNL_FLAG_BUSY, &sc->send[i]->flags);
clear_bit(CHNL_FLAG_BUSY, &sc->recv[i]->flags);
} }
// Enable interrupts // Enable interrupts
atomic_set(&sc->intr_disabled, 0); atomic_set(&sc->intr_disabled, 0);
@ -996,7 +999,7 @@ static inline int __devinit allocate_chnls(struct pci_dev *dev, struct fpga_stat
sc->recv[i] = (struct chnl_dir *) kzalloc(sizeof(struct chnl_dir), GFP_KERNEL); sc->recv[i] = (struct chnl_dir *) kzalloc(sizeof(struct chnl_dir), GFP_KERNEL);
if (sc->recv[i] == NULL) if (sc->recv[i] == NULL)
return i; return i;
sema_init(&sc->recv[i]->sem, 1); sc->recv[i]->flags = 0;
init_waitqueue_head(&sc->recv[i]->waitq); init_waitqueue_head(&sc->recv[i]->waitq);
if ((sc->recv[i]->msgs = init_circ_queue(5)) == NULL) { if ((sc->recv[i]->msgs = init_circ_queue(5)) == NULL) {
kfree(sc->recv[i]); kfree(sc->recv[i]);
@ -1019,7 +1022,7 @@ static inline int __devinit allocate_chnls(struct pci_dev *dev, struct fpga_stat
kfree(sc->recv[i]); kfree(sc->recv[i]);
return i; return i;
} }
sema_init(&sc->send[i]->sem, 1); sc->send[i]->flags = 0;
init_waitqueue_head(&sc->send[i]->waitq); init_waitqueue_head(&sc->send[i]->waitq);
if ((sc->send[i]->msgs = init_circ_queue(4)) == NULL) { if ((sc->send[i]->msgs = init_circ_queue(4)) == NULL) {
kfree(sc->send[i]); kfree(sc->send[i]);